[Federal Register Volume 64, Number 224 (Monday, November 22, 1999)]
[Rules and Regulations]
[Pages 63576-63584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30133]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-141-AD; Amendment 39-11296; AD 99-19-07]
RIN 2120-AA64
Airworthiness Directives; Gulfstream American (Frakes Aviation)
Model G-73 (Mallard) and G-73T Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain Gulfstream American (Frakes Aviation) Model G-73
(Mallard) and G-73T series airplanes, that requires revising the
Airplane Flight Manual (AFM) to include requirements for activation of
the airframe pneumatic deicing boots. This amendment is prompted by
reports of inflight incidents and an accident that occurred in icing
conditions where the airframe pneumatic deicing boots were not
activated. The actions specified by this AD are intended to ensure that
flightcrews activate the pneumatic wing and tail deicing boots at the
first signs of ice accumulation. This action will prevent reduced
controllability of the aircraft due to adverse aerodynamic effects of
ice adhering to the airplane prior to the first deicing cycle.
EFFECTIVE DATE: December 27, 1999.
ADDRESSES: Information pertaining to this rulemaking action may be
examined at the Federal Aviation Administration (FAA), Transport
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Rotorcraft Directorate, 1601 Meacham
Boulevard, Fort Worth, Texas.
FOR FURTHER INFORMATION CONTACT: Efran Esparza, Aerospace Engineer,
Airplane Certification Office, ASW-150, FAA, Rotorcraft Directorate,
1601 Meacham Boulevard, Fort Worth, Texas 76137-4298; telephone (817)
222-5130; fax (817) 222-5960.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to certain Gulfstream American
(Frakes Aviation) Model G-73 (Mallard) and G-73T series airplanes was
published in the Federal Register on July 16, 1999 (64 FR 38355). That
action proposed to require revising the Airplane Flight Manual (AFM) to
include requirements for activation of the airframe pneumatic deicing
boots.
Related Proposals
In addition to the proposed rule described previously, in June
1999, the FAA issued 18 other similar proposals that address the
subject unsafe condition on various airplane models (see below for a
listing of all 19 proposed rules). Those 18 proposals also were
published in the Federal Register on July 16, 1999. (Docket 99-NM-153-
AD, for Fokker Model F-27 Mark 100, 200, 300, 400, 500, 600, and 700
series airplanes, was also issued as a supplemental notice of proposed
rulemaking, and published in the Federal Register on August 6, 1999.)
This final rule contains the FAA's responses to all relevant public
comments received for each of these proposed rules.
----------------------------------------------------------------------------------------------------------------
Manufacturer airplane model Number Federal Register citation
----------------------------------------------------------------------------------------------------------------
Cessna Aircraft Company Models 500, 99-NM-136-AD 64 FR 38374
550, and 560 Series Airplanes.
[[Page 63577]]
Sabreliner Corporation Models 40, 60, 99-NM-137-AD 64 FR 38358
70, and 80 Series Airplanes.
Gulfstream Aerospace Model G-159 Series 99-NM-138-AD 64 FR 38341
Airplanes.
McDonnell Douglas Models DC-3 and DC-4 99-NM-139-AD 64 FR 38325
Series Airplanes.
Mitsubishi Heavy Industries Model YS-11 99-NM-140-AD 64 FR 38371
and YS-11A Series Airplanes.
Gulfstream American (Frakes Aviation) 99-NM-141-AD 64 FR 38355
Model G-73 (Mallard) and G-73T Series
Airplanes.
Lockheed, Models L-14 and L-18 Series 99-NM-142-AD 64 FR 38338
Airplanes.
Fairchild Models F-27 and FH-227 Series 99-NM-143-AD 64 FR 38322
Airplanes.
Aerospatiale Models ATR-42/ATR-72 99-NM-144-AD 64 FR 38368
Series.
Jetstream Model BAe ATP Airplanes...... 99-NM-145-AD 64 FR 38351
Jetstream Model 4101 Airplanes......... 99-NM-146-AD 64 FR 38335
British Aerospace Model HS 748 Series 99-NM-147-AD 64 FR 38319
Airplanes.
Saab Model SF340A/SAAB 340B/SAAB 2000 99-NM-148-AD 64 FR 38365
Series Airplanes.
CASA Model C-212/CN-235 Series 99-NM-149-AD 64 FR 38348
Airplanes.
Dornier Model 328-100 Series Airplanes. 99-NM-150-AD 64 FR 38332
Lockheed Model 1329-23 and 1329-25 99-NM-151-AD 64 FR 38316
(Lockheed Jetstar) Series Airplanes.
de Havilland Model DHC-7/DHC-8 Series 99-NM-152-AD 64 FR 38362
Airplanes.
Fokker Model F-27 Mark 100/200/300/400/ 99-NM-153-AD 64 FR 42870
500/600/700/050 Series Airplanes.
Short Brothers Model SD3-30/SD3-60/SD3- 99-NM-154-AD 64 FR 38329
SHERPA Airplanes.
----------------------------------------------------------------------------------------------------------------
Comments
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the following comments received.
1. Support for the Rule
One commenter supports the proposed rule.
2. Request To Withdraw the Proposal: No Unsafe Condition
Several commenters request that the proposal be withdrawn because
no unsafe condition exists on certain airplanes. One of these
commenters states that the FAA is merely speculating that the proposed
Airplane Flight Manual (AFM) revision will improve safety. Further, the
commenter contends that the FAA cannot substantiate that the proposed
AFM revision will prevent ice bridging. This same commenter also asks
if the FAA met its own standards by testing the proposed procedure on
each of the affected airplanes.
The FAA does not concur that no unsafe condition exists. As
discussed in the preamble of the proposed rule, the FAA has reviewed
the icing-related incident history of certain airplanes, and has
determined that icing incidents may have occurred because pneumatic
deicing boots were not activated at the first evidence of ice
accretion. As a result, the handling qualities or the controllability
of the airplane may have been reduced due to the accumulated ice. The
FAA also discussed an accident that occurred as a result of the failure
of the flightcrew to activate the wing and tail pneumatic deicing
boots.
Although there may have been no reported cases of incidents or
accidents on a specific airplane model, the potential still exists for
reduced controllability of all airplanes equipped with pneumatic
deicing boots due to adverse aerodynamic effects of ice adhering to the
airplane. This AD addresses this unsafe condition.
Further, ice bridging of deicing boots was considered during
development of the proposed rule. A broad representation of the
aviation community was consulted, including airframe manufacturers, air
carriers, airline pilot associations, airplane owner associations,
deicing boot manufacturers, and National Aeronautics and Space
Administration (NASA). Also, articles readily accessible by the general
piloting community solicited operational information concerning ice
bridging of deicing boots. The FAA considers that the general consensus
of the aviation community is that little or no evidence exists of ice
bridging of deicing boots with current deicing boot designs, and ice
that is not shed after the initial boot cycle continues to increase in
thickness and sheds during subsequent cycles.
In addition, many airplanes equipped with pneumatic deicing boots
to protect the engine are operated when icing conditions are present,
i.e., visible moisture and a specific temperature are observed. As
discussed in Comment #3 (following this response), at least two
airplane manufacturers have issued AFM's that contain procedures to
activate the deicing boots at the first sign of ice accumulation. The
FAA is unaware of any ice bridging problems associated with early
operations of either the airfoil or engine pneumatic deicing boots.
In response to the commenter's question regarding the FAA meeting
its own standards, the FAA infers that the commenter is requesting the
basis for the FAA's determination that the proposed procedures are
safe. Most aircraft certification programs have not considered the
reduced controllability of the aircraft due to adverse aerodynamic
effects of ice adhering to the pneumatic boots. The requirements of
this AD (activation of the deicing boot system at the first sign of ice
formation anywhere on the aircraft, or upon annunciation from an ice
detector system, whichever occurs first, along with the periodic
cycling of the boots) will minimize the ice accretions and thereby
reduce the adverse aerodynamic effects.
3. Request To Withdraw the Proposal: Possible Adverse Effects of
Residual Ice
Several commenters state that deicing boots do the best job of
shedding ice on a single cycle, if ice is permitted to accrete to \1/4\
or \1/2\ inch before activation of the boots. One of these commenters
further contends that the effect of continuous cycling in auto mode may
not produce a clean shed of ice on each activation, and that residual
ice must be taken into consideration before any revision to the AFM is
required. Another commenter states that, although operation in the
continuous mode upon first indication of ice accretion would eliminate
the problem of identification of accretion, the commenter is concerned
that there would then be a potential for degraded performance due to
residual ice.
The FAA does not concur that the proposal should be withdrawn
because of concerns over residual ice. Operation of pneumatic deicing
boots typically results in persistent ice accretions on the boot
surfaces, even when < to="inch" of="" ice="" is="" allowed="" to="" accrete="" prior="" to="" activation="" of="" the="" boots.="" the="" persistent="" residual="" and="" inter-cycle="" ice="" accretions="" [[page="" 63578]]="" typically="" result="" in="" adverse="" aerodynamic="" effects="" and="" degraded="" airplane="" flying="" qualities.="" activation="" of="" the="" wing="" and="" tail="" pneumatic="" deicing="" boots="" at="" the="" first="" sign="" of="" ice="" accretion,="" or="" at="" the="" annunciation="" of="" an="" ice="" detector="" system="" and="" periodic="" operation="" of="" the="" deicing="" boots="" will="" also="" result="" in="" persistent="" ice="" accretions.="" however,="" the="" proposed="" procedure="" will="" minimize="" the="" residual="" and="" intercycle="" ice="" accretions="" because="" the="" ice="" will="" be="" shed="" when="" the="" minimum="" thickness="" or="" mass="" required="" for="" shedding="" is="" reached.="" the="" residual="" and="" intercycle="" ice="" accretion="" thickness="" resulting="" from="" this="" procedure="" is="" less="" than="" the="" ice="" accretion="" thickness="" typically="" recommended="" prior="" to="" operation="" of="" the="" pneumatic="" deicing="" boot.="" adverse="" airplane="" flying="" qualities="" resulting="" from="" ice="" accretions="" typically="" are="" affected="" by="" the="" thickness,="" shape,="" texture,="" and="" location="" of="" the="" ice="" accretion.="" at="" least="" two="" airplane="" manufacturers="" have="" issued="" afm's="" that="" contain="" procedures="" to="" activate="" the="" deicing="" boots="" at="" the="" first="" sign="" of="" ice="" accumulation.="" those="" two="" airplane="" models="" have="" different="" wing="" and="" stabilizer="" design="" characteristics="" and="" different="" deicing="" boot="" configurations.="" further,="" those="" two="" airplane="" models="" represent="" a="" large="" proportion="" of="" the="" airplane="" fleet="" equipped="" with="" pneumatic="" deicing="" boots.="" the="" faa="" has="" received="" no="" reports="" indicating="" any="" adverse="" effects="" of="" residual="" ice="" resulting="" from="" early="" activation="" of="" the="" deicing="" boots="" for="" these="" airplane="" designs.="" in="" addition,="" a="" number="" of="" airplane="" models="" are="" equipped="" with="" deicing="" boot="" systems="" that="" include="" automatic="" operating="" modes,="" wherein="" the="" boots="" automatically="" cycle="" at="" specific="" time="" intervals="" after="" being="" activated.="" this="" automatic="" cycling="" has="" surely="" resulted="" in="" operation="" of="" the="" boots="" with="" less="" than="" the="" recommended="" thickness="" of="" ice="" accreted.="" the="" faa="" has="" received="" no="" reports="" indicating="" any="" adverse="" effects="" resulting="" from="" the="" use="" of="" the="" automatic="" mode.="" 4.="" request="" to="" withdraw="" or="" delay:="" develop="" more="" data="" several="" commenters="" request="" that="" the="" faa="" delay="" issuance="" of="" the="" rule="" until="" more="" data="" are="" developed="" and="" reviewed.="" certain="" of="" these="" commenters="" also="" state="" that="" at="" the="" public="" meeting="" on="" icing="" (february="" 2-4,="" 1999),="" the="" consensus="" was="" that="" a="" uniform="" procedure="" cannot="" be="" adopted="" for="" all="" airplanes.="" that="" is,="" a="" ``blanket''="" proposal="" for="" numerous="" airplanes="" (regardless="" of="" design)="" is="" inappropriate="" without="" specific="" consideration="" for="" the="" individual="" designs.="" another="" one="" of="" these="" commenters="" points="" out="" that="" each="" airplane="" model="" is="" unique="" and="" that="" the="" operating="" instructions="" for="" the="" ice="" protection="" system="" for="" one="" airplane="" model="" may="" not="" be="" appropriate="" for="" another="" airplane="" model.="" that="" commenter="" further="" adds="" that="" the="" airframe="" manufacturer="" is="" in="" the="" best="" position="" to="" determine="" appropriate="" limitations.="" another="" one="" of="" the="" commenters="" requests="" that,="" if="" the="" proposal="" is="" not="" withdrawn,="" the="" issuance="" of="" any="" rulemaking="" be="" delayed="" since="" certain="" language="" of="" the="" requirements="" of="" the="" ad="" is="" confusing.="" the="" faa="" does="" not="" concur="" that="" a="" delay="" in="" issuing="" this="" action="" is="" appropriate.="" the="" faa="" concurs="" that="" the="" airframe="" manufacturers="" present="" at="" the="" february="" public="" meeting="" did="" not="" support="" a="" common="" procedure="" for="" the="" operation="" of="" deicing="" boots.="" however,="" as="" mentioned="" previously,="" there="" have="" been="" no="" adverse="" reports="" on="" the="" airplane="" fleet="" equipped="" with="" pneumatic="" deicing="" boots="" that="" operate="" the="" boots="" at="" the="" first="" sign="" of="" ice="" accretion.="" with="" the="" exception="" of="" ``older''="" pneumatic="" boots="" (reference="" comment="" #7,="" below),="" the="" faa="" finds="" that="" a="" common="" procedure="" for="" boot="" operation="" is="" appropriate.="" the="" faa="" has="" determined="" that="" the="" common="" procedures="" for="" operation="" of="" deicing="" boots="" as="" required="" by="" this="" ad="" (activation="" of="" the="" deicing="" boot="" system="" at="" the="" first="" sign="" of="" ice="" formation="" anywhere="" on="" the="" aircraft,="" or="" upon="" annunciation="" of="" an="" ice="" detector="" system,="" whichever="" occurs="" first,="" and="" periodic="" cycling="" of="" the="" boots)="" will="" minimize="" the="" ice="" accretions="" and="" thereby="" reduce="" the="" adverse="" aerodynamic="" effects.="" to="" withdraw="" or="" delay="" this="" ad="" would="" be="" inappropriate="" since="" the="" faa="" has="" determined="" that="" an="" unsafe="" condition="" exists,="" and="" that="" the="" required="" afm="" revision="" must="" be="" accomplished="" to="" ensure="" continued="" safety="" of="" the="" fleet.="" the="" fact="" that="" other="" data="" may="" be="" developed="" at="" a="" later="" time="" does="" not="" negate="" the="" faa's="" responsibility="" to="" address="" the="" existing="" identified="" unsafe="" condition="" in="" a="" timely="" manner.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" the="" faa="" is="" unable="" to="" respond="" to="" one="" commenter's="" statement="" that="" certain="" language="" of="" the="" proposal="" was="" confusing="" since="" no="" example="" was="" specified.="" 5.="" request="" to="" withdraw="" proposals="" for="" certain="" airplanes="" three="" commenters,="" all="" airframe="" manufacturers,="" request="" that="" the="" proposal="" be="" withdrawn="" for="" several="" airplane="" models="" [british="" aerospace="" model="" atp="" airplanes,="" british="" aerospace="" model="" hs="" 748="" airplanes,="" dornier="" model="" 328-100="" series="" airplanes,="" and="" dehavilland="" model="" dhc-7/dhc-8="" series="" airplanes]="" since="" they="" have="" been="" certified="" to="" be="" in="" compliance="" with="" part="" 25="" of="" the="" federal="" aviation="" regulations="" (14="" cfr="" 25.1419).="" additionally,="" the="" commenters="" point="" out="" that="" those="" airplanes="" have="" been="" certificated="" in="" accordance="" with="" the="" appropriate="" foreign="" civil="" airworthiness="" authorities.="" the="" commenters="" further="" explain="" that="" service="" experience="" of="" those="" airplanes="" does="" not="" indicate="" any="" deficiencies="" with="" regard="" to="" handling="" and="" performance="" due="" to="" airframe="" accreted="" ice.="" in="" conclusion,="" the="" commenters="" state="" that,="" in="" the="" absence="" of="" any="" evidence="" to="" suggest="" deficiencies="" regarding="" this="" subject,="" they="" cannot="" support="" the="" intent="" of="" the="" rule.="" the="" faa="" acknowledges="" that="" an="" airplane="" model="" may="" have="" design="" characteristics="" that="" mitigate="" the="" adverse="" airplane="" flying="" qualities="" resulting="" from="" ice="" accretion="" on="" deicing="" boot="" surfaces.="" as="" discussed="" in="" the="" proposal="" for="" this="" ad,="" the="" faa="" has="" previously="" requested="" that="" interested="" persons="" provide="" information="" on="" icing="" system="" design="" and="" operations="" procedures="" concerning="" flight="" during="" icing="" conditions.="" the="" request="" also="" asked="" manufacturers,="" who="" are="" in="" the="" best="" position="" to="" determine="" those="" operating="" procedures,="" to="" provide="" data="" showing="" that="" their="" aircraft="" have="" safe="" operating="" characteristics="" with="" ice="" accreted="" on="" the="" protected="" surfaces="" (boots).="" that="" information="" was="" requested="" specifically="" by="" letter="" on="" october="" 1,="" 1998,="" to="" certain="" manufacturers="" of="" airplanes="" certified="" in="" accordance="" with="" part="" 25="" of="" the="" federal="" aviation="" regulations="" (14="" cfr="" part="" 25).="" except="" as="" discussed="" in="" item="" 6="" of="" the="" comment="" section="" of="" this="" final="" rule,="" no="" other="" information="" received="" caused="" the="" faa="" to="" reconsider="" that="" an="" unsafe="" condition="" may="" exist,="" or="" that="" a="" revision="" of="" the="" afm,="" such="" as="" required="" by="" this="" ad,="" was="" unsafe="" for="" those="" airplanes.="" additionally,="" similar="" information="" was="" specifically="" requested="" in="" the="" discussion="" section="" of="" the="" proposed="" rule.="" of="" the="" comments="" to="" the="" proposal="" that="" were="" received="" by="" the="" faa,="" no="" additional="" data="" was="" included="" for="" dornier="" model="" 328-100="" series="" airplanes,="" or="" de="" havilland="" model="" dhc-="" 7/dhc-8="" series="" airplanes="" that="" caused="" the="" faa="" to="" reconsider="" the="" previous="" conclusion="" that="" an="" unsafe="" condition="" exists.="" further,="" no="" data="" was="" provided="" to="" indicate="" that="" the="" proposal="" to="" require="" activation="" of="" wing="" and="" tail="" pneumatic="" deicing="" boots="" at="" the="" first="" sign="" of="" ice="" accretion="" or="" annunciation="" of="" an="" ice="" detector="" system="" was="" unsafe="" for="" any="" particular="" airplane="" model.="" united="" kingdom="" accident="" investigation="" board="" preliminary="" report="" ewc="" 91/18="" indicated="" that,="" while="" on="" climb="" to="" 16,000="" feet="" in="" the="" vicinity="" of="" oxford,="" england,="" on="" august="" 11,="" 1991,="" a="" british="" aerospace="" model="" atp="" airplane="" suffered="" a="" significant="" degradation="" of="" flying="" qualities="" and="" propeller="" icing.="" [[page="" 63579]]="" according="" to="" that="" report,="" the="" deicing="" boots="" of="" the="" airplane="" were="" not="" activated,="" and="" the="" airplane="" stalled,="" experienced="" severe="" uncontrolled="" roll="" oscillations,="" severe="" vibration="" that="" rendered="" the="" electronic="" flight="" instruments="" partially="" unreadable,="" and="" developed="" a="" high="" rate="" of="" descent.="" the="" deicing="" boots="" were="" finally="" activated="" and="" control="" of="" the="" airplane="" was="" regained="" after="" a="" loss="" of="" 3,500="" feet="" in="" altitude.="" the="" report="" identified="" causal="" factors="" of="" the="" incident="" which="" included="" rapid="" accumulation="" of="" glaze="" ice="" that="" was="" not="" evident="" to="" the="" flightcrew,="" difficulty="" of="" the="" flightcrew="" to="" visually="" gauge="" the="" ice="" accretion="" thickness="" on="" the="" wing's="" leading="" edge,="" and="" propeller="" vibrations="" that="" disguised="" the="" onset="" of="" wing="" stall.="" even="" though="" this="" incident="" occurred="" outside="" of="" the="" united="" states,="" and="" although="" this="" airplane="" model="" demonstrated="" acceptable="" in-flight="" icing="" airworthiness="" relative="" to="" faa="" and="" joint="" airworthiness="" authorities="" (jaa)="" requirements,="" the="" incident="" illustrates="" the="" vulnerability="" of="" this="" airplane="" model="" to="" the="" safety="" condition="" addressed="" by="" this="" ad.="" one="" commenter,="" british="" aerospace,="" has="" requested="" until="" october="" 20,="" 1999,="" to="" provide="" additional="" data="" to="" substantiate="" that="" the="" model="" atp="" airplanes="" and="" model="" hs="" 748="" airplanes="" can="" safely="" operate="" with="" ice="" accumulations="" on="" the="" protected="" surfaces.="" as="" discussed="" previously="" and="" in="" the="" nprm,="" the="" faa="" considers="" that="" this="" same="" vulnerability="" exists="" on="" all="" airplanes="" equipped="" with="" pneumatic="" deicing="" boots.="" in="" the="" interest="" of="" safety,="" the="" faa="" finds="" that="" it="" is="" not="" prudent="" to="" delay="" issuance="" of="" the="" final="" rules="" on="" those="" airplane="" models.="" however,="" british="" aerospace="" and="" any="" other="" manufacturer="" is="" encouraged="" to="" request="" approval="" of="" an="" alternative="" method="" of="" compliance="" with="" the="" airworthiness="" directive="" based="" on="" substantiating="" data="" indicating="" that="" a="" particular="" aircraft="" can="" safely="" be="" operated="" with="" the="" ice="" that="" would="" accumulate="" on="" the="" protected="" surfaces="" prior="" to="" activation="" of="" the="" ice="" protection="" system.="" 6.="" request="" to="" withdraw="" the="" proposal="" for="" certain="" other="" airplanes="" two="" manufacturers="" request="" that="" the="" proposals="" regarding="" cessna="" model="" 500,="" 501,="" 550,="" 551,="" and="" 560="" series="" airplanes,="" and="" british="" aerospace="" (jetstream)="" model="" 4101="" airplanes="" be="" withdrawn.="" the="" manufacturers="" advise="" that="" the="" testing="" summarized="" in="" their="" comments="" provides="" evidence="" that="" the="" current="" procedures="" provide="" a="" safe="" method="" to="" operate="" those="" airplane="" models.="" the="" manufacturers="" conclude="" that,="" based="" on="" the="" service="" history="" and="" data="" provided="" to="" the="" faa,="" the="" proposed="" afm="" revision="" for="" those="" models="" is="" unnecessary.="" the="" faa="" concurs="" that="" the="" notice="" of="" proposed="" rulemaking="" for="" cessna="" model="" 500,="" 501,="" 550,="" 551,="" and="" 560="" series="" airplanes="" should="" be="" withdrawn="" based="" on="" the="" following="" information.="" the="" manufacturer="" performed="" a="" complete="" evaluation="" of="" the="" stall="" and="" handling="" characteristics="" with="" simulated="" ice="" shapes="" on="" the="" model="" 550="" (bravo)="" series="" airplanes.="" stall="" speeds="" and="" warning="" margins="" were="" evaluated="" with="" a="" \1/2\-inch="" glaze="" ice="" shape="" and="" with="" an="" ice="" shape="" associated="" with="" the="" system="" failure.="" this="" \1/2\-inch="" ice="" shape="" simulated="" the="" ice="" shape="" prior="" to="" deicing="" boot="" activation.="" maneuver="" margin="" testing="" consisted="" of="" left="" and="" right="" 40-="" degree="" bank="" turns.="" stall="" characteristics="" were="" evaluated="" with="" a="" \1/2\-="" inch="" rime="" ice="" shape="" configuration.="" stall="" characteristic="" testing="" consisted="" of="" wings="" level="" and="" 30-degree="" bank="" turns.="" at="" the="" conclusion="" of="" the="" testing="" it="" was="" determined="" that="" the="" airplane="" had="" an="" acceptable="" stall="" warning="" margin="" with="" ice="" shapes="" present.="" the="" manufacturer="" maintains="" that="" model="" 500/501,="" model="" 550/551,="" and="" model="" 550="" (bravo)="" series="" airplanes="" all="" use="" a="" common="" wing="" airfoil="" with="" some="" minor="" differences="" in="" span="" and="" wing="" loading.="" these="" aircraft="" also="" use="" a="" common="" tail="" configuration="" (airfoil,="" span,="" and="" leading="" edge="" sweep).="" additionally,="" the="" faa="" reviewed="" the="" type="" inspection="" report="" (tir)="" for="" model="" 550="" (bravo)="" series="" airplane="" testing="" and="" found="" that="" ice="" shapes="" were="" placed="" on="" both="" the="" protected="" and="" unprotected="" surfaces.="" the="" model="" 560="" (ultra)="" series="" airplanes="" underwent="" an="" extensive="" ice="" shape="" stall="" investigation.="" this="" investigation="" consisted="" of="" stall="" testing="" of="" the="" baseline="" airplane="" and="" the="" airplane="" with="" the="" most="" adverse="" simulated="" intercycle="" ice="" shapes.="" the="" ice="" shapes="" consisted="" of="" \1/2\-inch="" shapes="" on="" the="" surfaces="" protected="" by="" boots="" and="" 3-inch="" shapes="" on="" unprotected="" flight="" surfaces.="" the="" stall="" speeds="" determined="" by="" this="" testing="" were="" incorporated="" into="" the="" safeflight="" angle="" of="" attack="" computer="" to="" increase="" the="" stall="" warning="" margin="" during="" flight="" in="" icing="" conditions.="" the="" model="" 560="" series="" airplanes="" angle="" of="" attack="" computer="" was="" also="" updated="" to="" incorporate="" a="" normal="" mode="" and="" an="" ice="" mode="" stall="" warning="" system.="" the="" changes="" to="" the="" angle="" of="" attack="" computer="" on="" model="" 560="" and="" 560="" (ultra)="" series="" airplanes="" were="" proposed="" by="" rules="" docket="" no.="" 98-nm-="" 312-ad.="" the="" faa="" notes="" that="" extensive="" testing="" of="" model="" 550="" and="" 560="" series="" airplanes="" (in="" which="" acceptable="" stall="" protection="" and="" maneuver="" margins="" at="" operational="" speeds="" were="" demonstrated="" with="" expected="" ice="" accretion="" on="" the="" deicing="" boot="" surfaces)="" indicates="" that="" these="" airplanes="" can="" safely="" operate="" with="" ice="" accretions="" associated="" with="" the="" afm="" normal="" operations="" procedures="" of="" the="" deicing="" boots.="" these="" attributes="" demonstrate="" that="" model="" 550="" and="" 560="" series="" airplanes="" satisfactorily="" address="" the="" unsafe="" condition="" addressed="" by="" this="" ad.="" since="" model="" 500="" series="" airplanes="" are="" similar="" to="" model="" 550="" series="" airplanes,="" the="" model="" 500="" series="" airplanes="" also="" satisfactorily="" addresss="" the="" unsafe="" condition="" addressed="" by="" this="" ad.="" the="" faa="" also="" notes="" that="" testing="" of="" model="" 560="" series="" airplanes="" revealed="" problems="" in="" the="" stall="" warning="" margin="" for="" flight="" in="" icing="" conditions="" that="" were="" addressed="" by="" previously="" issued="" airworthiness="" directives.="" the="" faa="" also="" concurs="" that="" the="" notice="" of="" proposed="" rulemaking="" for="" british="" aerospace="" jetstream="" model="" 4101="" airplanes="" should="" be="" withdrawn="" based="" on="" the="" following="" information.="" in="" response="" to="" the="" faa's="" october="" 1,="" 1998,="" letter="" (discussed="" previously),="" british="" aerospace="" submitted="" a="" summary="" of="" the="" handling="" and="" performance="" flight="" test="" results="" that="" were="" produced="" during="" the="" original="" flight="" in="" icing="" certification.="" this="" summary="" was="" referenced="" in="" their="" response="" to="" the="" proposed="" rulemaking.="" the="" commenter="" volunteered="" to="" provide="" any="" reports="" referenced="" in="" the="" summary.="" the="" faa="" requested="" and="" subsequently="" received="" copies="" of="" the="" full="" handling="" and="" performance="" flight="" test="" results="" for="" certification="" in="" the="" icing="" conditions="" specified="" in="" appendix="" c="" of="" part="" 25="" of="" the="" federal="" aviation="" regulations="" (14="" cfr="" 25),="" and="" the="" jaa="" draft="" issue="" of="" amj25.1419,="" which="" was="" used="" as="" guidance="" for="" compliance="" with="" jar/far="" 25.1419.="" the="" faa="" reviewed="" these="" reports="" and="" guidance="" material="" and="" finds="" that="" the="" jetstream="" 4101="" airplane="" was="" adequately="" tested="" with="" a="" variety="" of="" natural="" ice="" accretions="" on="" both="" the="" protected="" and="" unprotected="" surfaces.="" handling="" and="" performance="" flight="" test="" was="" accomplished="" for="" the="" following:="" normal="" operation="" of="" the="" deicing="" boots,="" \1/2\="" to="" \3/4\-inch="" of="" ice="" on="" the="" protected="" wing="" leading="" edges="" and="" up="" to="" 3="" inches="" of="" ice="" on="" unprotected="" leading="" edges;="" simulated="" failure="" of="" the="" deicing="" boots,="" approximately="" 1="" to="" 1\1/2\="" inches="" of="" ice="" on="" all="" leading="" edges;="" ice="" accreted="" during="" the="" take-off="" phase,="" a="" thin="" rough="" layer="" of="" ice="" accreted="" during="" the="" initial="" take-off="" phase="" to="" 400="" feet,="" prior="" to="" operation="" of="" deicing="" boots.="" these="" ice="" accretion="" depths="" were="" established="" to="" address="" the="" following:="" ice="" accreted="" during="" the="" rest-time="" of="" a="" deicing="" cycle,="" delayed="" operation="" or="" failure="" of="" the="" system,="" and="" residual="" ice="" accumulations.="" the="" flight="" testing="" examined="" stall="" speeds,="" stall="" warning="" margins,="" stall="" characteristics,="" maneuver="" margins,="" longitudinal="" controllability,="" flap="" configuration="" changes,="" ability="" to="" [[page="" 63580]]="" trim,="" susceptibility="" to="" tailplane="" stall,="" and="" longitudinal,="" lateral,="" and="" directional="" stability.="" the="" angles="" of="" attack="" for="" activation="" of="" the="" stall="" warning="" system="" and="" stall="" identification="" system="" (i.e.,="" stick="" shaker="" or="" stick="" pusher)="" are="" reset="" to="" lower="" values="" (i.e.,="" higher="" speeds)="" for="" flight="" in="" icing="" and="" safe="" flight="" speeds="" (minimum="" operating="" speeds)="" established="" accordingly.="" affected="" afm="" performance="" information="" was="" derived="" for="" icing="" conditions="" based="" on="" the="" higher="" operating="" speeds,="" in="" accordance="" with="" jaa="" draft="" amj25.1419.="" the="" cessna="" and="" british="" aerospace="" aircraft="" models="" discussed="" in="" this="" comment="" have="" been="" tested="" and,="" where="" appropriate,="" changes="" have="" been="" made="" to="" ensure="" the="" airplanes="" are="" safe="" for="" operations="" with="" ice="" accretions="" on="" the="" protected="" surfaces.="" without="" this="" type="" of="" testing="" and="" substantiation,="" the="" faa="" must="" conclude="" the="" aircraft="" affected="" by="" this="" final="" rule="" may="" be="" subject="" to="" adverse="" aerodynamic="" effects="" due="" to="" ice="" accretions="" on="" the="" protected="" surfaces="" prior="" to="" deicing="" boot="" operation.="" other="" manufacturers="" may="" also="" develop="" the="" necessary="" data="" to="" substantiate="" that="" their="" airplanes="" are="" safe="" with="" these="" accretions="" and="" request="" approval="" of="" an="" alternative="" method="" of="" compliance.="" 7.="" request="" to="" differentiate="" between="" ``modern''="" boot="" systems="" and="" ``older''="" boot="" systems="" several="" commenters="" request="" that="" the="" difference="" between="" the="" ``older''="" boot="" systems="" and="" the="" ``modern''="" boot="" systems="" be="" explained.="" these="" commenters="" express="" concern="" that="" although="" both="" systems="" are="" addressed="" in="" the="" proposal,="" there="" may="" not="" be="" a="" sound="" technical="" reason="" to="" apply="" the="" requirements="" of="" the="" proposal="" to="" both="" types="" of="" boot="" systems.="" the="" faa="" acknowledges="" that="" definitions="" of="" ``older''="" and="" ``modern''="" pneumatic="" boot="" systems="" should="" be="" provided.="" therefore,="" for="" the="" purposes="" of="" this="" ad,="" ``modern''="" pneumatic="" boot="" systems="" may="" be="" characterized="" by="" short="" segmented,="" small="" diameter="" tubes,="" which="" are="" operated="" at="" relatively="" high="" pressures="" [18-23="" pounds="" per="" square="" inch="" (psi)]="" by="" excess="" bleed="" air="" that="" is="" provided="" by="" turbine="" engines.="" ``older''="" pneumatic="" boot="" systems="" may="" be="" characterized="" by="" long,="" uninterrupted,="" large="" diameter="" tubes,="" which="" were="" operated="" at="" low="" pressures="" by="" engine="" driven="" pneumatic="" pumps="" whose="" pressure="" varied="" with="" engine="" revolutions="" per="" minute="" (rpm).="" this="" low="" pressure="" coupled="" with="" long="" and="" large="" diameter="" tubes="" caused="" early="" de-ice="" systems="" to="" have="" very="" lengthy="" inflation="" and="" deflation="" cycles="" and="" dwell="" times.="" (dwell="" time="" is="" the="" period="" of="" time="" that="" the="" boot="" remains="" fully="" expanded="" following="" the="" completion="" of="" the="" inflation="" cycle="" until="" the="" beginning="" of="" the="" deflation="" cycle.)="" 8.="" request="" to="" withdraw="" the="" proposal="" for="" airplanes="" with="" ``older''="" boots="" two="" commenters="" request="" that="" the="" proposed="" rules="" applying="" to="" gulfstream="" model="" g-159="" series="" airplanes="" and="" mcdonnell="" douglas="" model="" dc-="" 3="" and="" dc-4="" series="" airplanes="" be="" withdrawn.="" both="" commenters="" state="" that="" those="" airplane="" models="" do="" not="" meet="" the="" common="" definition="" of="" the="" word="" ``modern.''="" (see="" comment="" #7="" of="" this="" final="" rule="" for="" a="" definition="" of="" ``modern''="" as="" used="" in="" this="" ad.)="" one="" commenter="" states="" that="" the="" current="" afm="" specifically="" directs="" the="" flightcrew="" to="" wait="" for="" \1/4\-inch="" of="" ice="" before="" activating="" the="" boots.="" further,="" the="" commenter="" asserts="" that="" the="" current="" procedure="" was="" developed="" during="" certification="" and="" is="" the="" basis="" for="" the="" airplane's="" approval="" for="" flight="" into="" known="" icing.="" additionally,="" the="" commenters="" assert="" that="" the="" in-service="" safety="" records="" for="" more="" than="" 40="" years="" indicates="" that="" the="" existing="" procedures="" are="" appropriate="" for="" these="" airplanes.="" the="" commenter="" concludes="" that="" the="" proposed="" afm="" revision="" is="" in="" direct="" opposition="" to="" the="" certification="" findings.="" the="" faa="" acknowledges="" that="" early="" activation="" of="" the="" ``older''="" pneumatic="" deicing="" boots="" may="" create="" the="" hazard="" of="" ice="" bridging="" on="" the="" ``older''="" systems.="" as="" discussed="" in="" comment="" #2="" previously,="" ``older''="" boots="" may="" be="" susceptible="" to="" ice="" bridging,="" and="" the="" faa="" concurs="" that="" requiring="" the="" activation="" of="" the="" boots="" at="" the="" first="" sign="" of="" icing="" may="" actually="" introduce="" an="" unsafe="" condition="" on="" those="" airplanes.="" in="" order="" to="" address="" this="" issue,="" the="" faa="" is="" taking="" the="" following="" steps.="" first,="" to="" accommodate="" certain="" airplane="" models="" of="" the="" fleet="" (i.e.,="" gulfstream="" model="" g-159="" series="" airplanes="" and="" mcdonnell="" douglas="" model="" dc-3="" and="" dc-4="" series="" airplanes)="" that="" may="" be="" equipped="" with="" the="" ``older''="" pneumatic="" deicing="" boot="" system,="" the="" faa="" is="" considering="" the="" issuance="" of="" supplemental="" nprm's="" for="" those="" airplane="" models.="" the="" purpose="" of="" the="" supplemental="" nprm's="" would="" be="" to="" require="" an="" inspection="" to="" determine="" which="" type="" of="" pneumatic="" deicing="" boots="" are="" installed="" on="" the="" airplanes,="" and="" to="" require="" operation="" of="" the="" boots="" at="" the="" first="" sign="" of="" ice="" accretion="" if="" the="" airplanes="" have="" been="" retrofitted="" with="" ``modern''="" boots.="" second,="" for="" aircraft="" with="" ``older''="" pneumatic="" boots="" installed,="" the="" faa="" will="" continue="" to="" investigate="" other="" solutions="" to="" the="" unsafe="" condition="" of="" reduced="" handling="" qualities="" or="" controllability="" of="" the="" airplane="" due="" to="" ice="" accumulations="" on="" the="" protected="" surfaces.="" if="" other="" solutions="" are="" identified,="" the="" faa="" may="" consider="" further="" rulemaking.="" 9.="" request="" to="" revise="" afm="" change="" one="" commenter="" requests="" that="" the="" proposal="" to="" operate="" the="" boots="" at="" the="" first="" sign="" of="" ice="" accretion="" be="" limited="" to="" the="" holding="" and="" approach="" phases="" of="" flight.="" the="" commenter="" states="" that="" the="" aviation="" rulemaking="" advisory="" committee="" (arac)="" ice="" protection="" harmonization="" working="" group="" (iphwg)="" completed="" a="" comprehensive="" review="" of="" past="" icing="" accidents/="" incidents.="" the="" iphwg="" concluded="" that="" the="" only="" phases="" of="" flight="" that="" demonstrate="" a="" safety="" concern="" are="" holding="" patterns="" and="" various="" approach="" segments;="" since="" these="" operations="" are="" conducted="" at="" lower="" airplane="" speed,="" instability="" could="" occur="" as="" a="" result="" of="" ice="" accumulations="" on="" the="" wing="" and="" tail="" surfaces.="" the="" faa="" does="" not="" concur="" that="" the="" afm="" revision="" should="" be="" limited="" to="" the="" holding="" and="" approach="" phases="" of="" flight.="" the="" faa="" acknowledges="" that="" the="" iphwg="" is="" working="" on="" a="" proposed="" operations="" rule="" that="" may="" only="" be="" applicable="" during="" holding="" and="" approach="" phases="" of="" flight.="" however,="" the="" iphwg="" continues="" to="" work="" on="" the="" proposed="" rule="" and="" has="" not="" reached="" technical="" agreement.="" since="" discussions="" are="" ongoing,="" it="" would="" not="" be="" appropriate="" to="" assume="" that="" the="" iphwg="" positions="" as="" presented="" by="" the="" commenter="" will="" necessarily="" be="" reflected="" in="" the="" actual="" published="" proposal.="" another="" commenter,="" an="" airplane="" manufacturer,="" stated="" that="" the="" afm="" for="" model="" sf340a/saab340b/saab="" 2000="" series="" airplanes="" currently="" does="" not="" limit="" the="" operation="" of="" the="" deicing="" boots="" during="" specific="" phases="" of="" flight.="" the="" commenter="" requests="" that="" the="" afm="" change="" required="" by="" paragraph="" (a)="" of="" the="" proposal="" be="" revised="" to="" limit="" the="" applicable="" phases="" of="" flight="" where="" the="" afm="" specifies="" that="" deicing="" boots="" should="" not="" be="" used.="" specifically,="" the="" commenter="" requests="" that="" the="" language="" be="" revised="" to="" read="" ``deicing="" boots="" must="" not="" be="" used="" during="" take-off="" and="" landing.''="" the="" faa="" partially="" concurs,="" and="" acknowledges="" that="" clarification="" is="" necessary.="" it="" was="" the="" faa's="" intent="" that="" the="" boots="" do="" not="" have="" to="" be="" operated="" at="" the="" first="" sign="" of="" ice="" accretion="" during="" those="" phases="" of="" flight="" if="" there="" are="" existing="" procedures="" in="" the="" afm="" that="" prohibit="" the="" operation="" of="" the="" boots="" during="" specific="" phases="" of="" flight.="" however,="" the="" boots="" must="" always="" be="" operated="" at="" the="" first="" sign="" of="" ice="" accretion="" if,="" in="" accordance="" with="" the="" afm,="" it="" is="" acceptable="" to="" operate="" the="" boots="" during="" all="" phases="" of="" flight.="" therefore,="" the="" faa="" has="" revised="" paragraph="" (a)="" of="" the="" final="" rule="" to="" state,="" ``except="" if="" the="" afm="" otherwise="" specifies="" that="" deicing="" boots="" should="" not="" be="" used="" for="" certain="" phases="" of="" flight="" (e.g.,="" take-off,="" final="" approach,="" and="" [[page="" 63581]]="" landing),="" compliance="" with="" the="" following="" is="" required.''="" with="" respect="" to="" the="" request="" to="" specify="" that="" the="" deicing="" boots="" must="" not="" be="" used="" during="" take-off="" and="" landing,="" it="" would="" be="" desirable="" to="" customize="" the="" afm="" limitation="" for="" specific="" models="" of="" airplanes.="" this="" would="" allow="" the="" afm="" to="" clearly="" indicate="" to="" the="" flightcrew="" when="" the="" deicing="" boots="" should="" be="" deactivated,="" rather="" than="" necessitating="" that="" the="" flightcrew="" first="" determine="" if="" there="" are="" other="" portions="" of="" the="" afm="" that="" indicate="" that="" the="" deicing="" boots="" should="" not="" be="" used="" during="" specific="" phases="" of="" flight.="" therefore,="" the="" faa="" encourages="" requests="" for="" approval="" of="" alternative="" methods="" of="" compliance="" to="" customize="" the="" afm="" limitation="" to="" the="" specific="" airplane="" model.="" however,="" the="" faa="" does="" not="" concur="" with="" the="" request="" to="" revise="" the="" final="" rule="" that="" applies="" to="" saab="" model="" saab="" sf340a/saab340b/saab="" 2000="" series="" airplanes="" since="" the="" existing="" saab="" afm="" does="" not="" indicate="" that="" the="" deicing="" boots="" should="" not="" be="" used="" during="" take-off="" and="" landing.="" if="" the="" commenter="" has="" data="" to="" indicate="" that="" the="" deicing="" boots="" should="" not="" be="" used="" during="" those="" phases="" of="" flight,="" the="" commenter="" should="" take="" action="" to="" revise="" the="" afm="" and="" request="" approval="" of="" an="" alternative="" method="" of="" compliance.="" 10.="" request="" to="" revise="" instructions="" on="" when="" to="" deactivate="" the="" boot="" system="" one="" commenter="" requests="" that="" two="" changes="" be="" made="" to="" paragraph="" (a)="" of="" the="" proposal.="" the="" first="" change="" would="" be="" to="" specify="" that="" the="" wing="" and="" tail="" leading="" edge="" pneumatic="" deicing="" boot="" system="" may="" be="" deactivated="" only="" after="" completion="" of="" an="" entire="" deicing="" cycle="" after="" leaving="" icing="" conditions.="" the="" commenter="" also="" requests="" that="" the="" proposal="" be="" revised="" to="" add="" related="" procedures="" for="" operating="" speeds,="" and="" that="" related="" procedures="" for="" operation="" of="" the="" autopilot="" (if="" any)="" be="" discontinued="" only="" after="" the="" airplane="" is="" determined="" to="" be="" clear="" of="" ice.="" the="" commenter="" states="" that="" natural="" ice="" shedding,="" melting,="" or="" sublimation="" from="" the="" protected="" areas="" will="" mostly="" eliminate="" residual="" ice.="" regarding="" the="" commenter's="" first="" request,="" the="" faa="" concurs.="" for="" the="" reasons="" the="" commenter="" stated,="" the="" faa="" has="" revised="" paragraph="" (a)="" of="" the="" final="" rule="" from:="" ``the="" wing="" and="" tail="" leading="" edge="" pneumatic="" deicing="" boot="" system="" may="" be="" deactivated="" only="" after="" leaving="" icing="" conditions="" and="" after="" the="" airplane="" is="" determined="" to="" be="" clear="" of="" ice;''="" to="" ``the="" wing="" and="" tail="" leading="" edge="" pneumatic="" deicing="" boot="" system="" may="" be="" deactivated="" only="" after="" completion="" of="" an="" entire="" deicing="" cycle="" after="" leaving="" icing="" conditions.''="" regarding="" the="" commenter's="" second="" request,="" the="" faa="" considers="" that,="" since="" the="" suggested="" change="" would="" alter="" the="" actions="" currently="" required="" by="" this="" ad,="" additional="" rulemaking="" would="" be="" required.="" the="" faa="" finds="" that="" to="" delay="" this="" action="" would="" be="" inappropriate="" in="" light="" of="" the="" identified="" unsafe="" condition.="" however,="" the="" faa="" is="" considering="" additional="" rulemaking="" concerning="" operating="" speeds="" during="" icing="" conditions.="" 11.="" requests="" the="" faa="" consider="" the="" pilot="" workload="" one="" commenter="" states="" that="" the="" proposal="" would="" require="" the="" pilot="" to="" monitor="" ice="" formation="" and="" to="" activate="" the="" deicing="" system="" almost="" constantly.="" another="" commenter="" suggests="" that="" such="" increase="" of="" the="" pilot's="" workload="" could,="" of="" itself,="" cause="" an="" indirect="" adverse="" impact="" on="" operational="" safety.="" the="" commenters="" request="" that="" the="" faa="" consider="" the="" additional="" pilot="" workload="" if="" the="" proposal="" is="" adopted.="" the="" faa="" has="" previously="" considered="" the="" effects="" on="" the="" pilot="" of="" requiring="" that="" the="" deicing="" boots="" be="" activated="" at="" the="" first="" sign="" of="" ice="" formation="" anywhere="" on="" the="" airplane,="" or="" upon="" annunciation="" from="" an="" ice="" detector="" system.="" the="" faa="" acknowledges="" that="" current="" procedures="" recommending="" activation="" of="" the="" deicing="" boots="" at="" a="" specific="" ice="" accretion="" thickness="" require="" the="" flightcrew="" to="" closely="" monitor="" the="" ice="" accretion.="" however,="" since="" a="" number="" of="" airplanes="" affected="" by="" this="" ad="" are="" equipped="" with="" deicing="" boot="" systems="" with="" automatic="" operating="" modes,="" operating="" the="" deicing="" boots="" at="" the="" first="" sign="" of="" ice="" accretion="" in="" an="" appropriate="" automatic="" mode="" will="" favorably="" influence="" flightcrew="" workload.="" for="" airplanes="" not="" equipped="" with="" automatic="" deicing="" boot="" operating="" modes,="" periodic="" operation="" of="" the="" boots="" can="" be="" accomplished="" based="" on="" time="" intervals="" consistent="" with="" existing="" icing="" conditions.="" the="" faa="" considers="" that="" periodic="" operation="" of="" the="" boots="" is="" not="" a="" greater="" workload="" burden="" than="" closely="" monitoring="" the="" ice="" accretion="" thickness.="" for="" the="" reasons="" stated,="" the="" faa="" has="" determined="" that="" it="" is="" unnecessary="" to="" revise="" the="" final="" rule.="" 12.="" request="" to="" withdraw="" the="" proposal:="" provide="" training="" instead="" several="" commenters="" request="" that="" the="" faa="" withdraw="" the="" proposal="" and="" ensure="" that="" appropriate="" information="" and="" training="" regarding="" the="" use="" of="" the="" boots="" is="" provided="" to="" pilots.="" the="" commenters="" also="" suggest="" that="" a="" testing="" program="" be="" accomplished="" by="" industry.="" the="" commenters="" assert="" that="" such="" training,="" along="" with="" an="" analysis="" of="" the="" testing="" program,="" would="" eliminate="" the="" need="" for="" requiring="" that="" the="" deicing="" boots="" be="" activated="" in="" accordance="" with="" the="" proposal.="" one="" commenter="" also="" adds="" that="" the="" afm="" should="" only="" be="" changed="" to="" add="" a="" warning="" that="" delayed="" activation="" of="" the="" pneumatic="" boot="" system="" may="" be="" unsafe.="" another="" commenter="" adds="" that="" the="" language="" of="" the="" proposed="" afm="" revision="" may="" conflict="" with="" current="" afm="" procedures="" and="" could="" confuse="" operators.="" the="" faa="" does="" not="" concur="" that="" substituting="" mandatory="" training="" for="" issuance="" of="" an="" ad="" is="" appropriate="" in="" this="" case.="" the="" faa="" acknowledges="" that,="" in="" addition="" to="" the="" issuance="" of="" an="" ad,="" information="" specified="" in="" the="" revision="" to="" the="" afm="" should="" be="" integrated="" into="" the="" pilot="" training="" syllabus.="" however,="" the="" development="" and="" use="" of="" advisory="" materials="" and="" training="" alone="" are="" not="" adequate="" to="" address="" the="" unsafe="" condition.="" the="" only="" method="" of="" ensuring="" that="" certain="" information="" is="" available="" to,="" and="" mandatory="" for,="" the="" pilot="" is="" through="" incorporation="" of="" the="" information="" into="" the="" limitations="" section="" of="" the="" afm.="" the="" appropriate="" vehicle="" for="" requiring="" such="" revision="" of="" the="" afm="" is="" issuance="" of="" an="" ad.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" 13.="" request="" to="" consider="" procedures="" already="" in="" normal="" procedures="" section="" one="" commenter="" requests="" concurrence="" that="" procedures="" existing="" in="" the="" normal="" procedures="" section="" of="" the="" afm="" be="" considered="" as="" compliant="" with="" the="" requirements="" of="" the="" proposed="" ad.="" the="" faa="" does="" not="" concur="" that="" procedures="" specified="" in="" the="" normal="" procedures="" section="" of="" the="" afm="" are="" an="" equivalent="" method="" of="" compliance="" with="" the="" ad.="" the="" faa="" considers="" that,="" since="" the="" limitations="" section="" of="" the="" afm="" is="" the="" only="" section="" of="" the="" afm="" that="" is="" mandatory="" [part="" 91.9="" of="" the="" federal="" aviation="" regulations="" (14="" cfr="" 91.9)],="" the="" subject="" required="" revision="" to="" the="" afm="" must="" be="" included="" in="" the="" limitations="" section.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" 14.="" request="" to="" limit="" the="" ad="" to="" only="" those="" operations="" conducive="" to="" icing="" two="" commenters="" request="" that="" the="" afm="" limitation="" specified="" in="" paragraph="" (a)="" of="" the="" proposal="" be="" limited="" to="" those="" conditions="" where="" operations="" conducive="" to="" icing="" exist.="" the="" commenters="" provide="" examples="" of="" conditions="" where="" operations="" not="" conducive="" to="" icing="" may="" exist="" such="" as="" hawaii;="" the="" caribbean;="" short,="" low="" altitude="" flights="" in="" the="" summer;="" etc.="" one="" of="" these="" commenters="" states="" that,="" ``under="" the="" proposal,="" dispatch="" with="" an="" inoperative="" boot="" would="" be="" considered="" prohibited="" even="" though="" the="" deicing="" would="" never="" be="" needed.''="" [[page="" 63582]]="" the="" faa="" does="" not="" concur="" that="" revision="" of="" the="" ad="" is="" necessary="" in="" this="" regard.="" paragraph="" (a)="" of="" the="" ad="" specifically="" states="" that="" wing="" and="" tail="" leading="" edge="" pneumatic="" deicing="" boot="" systems="" must="" be="" activated="" at="" the="" first="" sign="" of="" ice="" formation="" anywhere="" on="" the="" aircraft,="" or="" upon="" annunciation="" from="" an="" ice="" detector="" system,="" whichever="" occurs="" first.="" the="" faa="" considers="" that,="" regardless="" of="" what="" geographic="" area="" an="" airplane="" may="" be="" flying="" in="" or="" what="" season="" of="" the="" year="" it="" may="" be,="" the="" boot="" system="" must="" be="" activated="" if="" those="" specified="" conditions="" occur.="" regarding="" dispatch="" with="" an="" inoperative="" boot,="" current="" master="" minimum="" equipment="" list="" (mmel)="" procedures="" prohibit="" dispatch="" of="" the="" airplane="" into="" known="" or="" forecast="" icing="" conditions="" if="" the="" deicing="" boots="" are="" inoperative.="" in="" the="" event="" that="" icing="" conditions="" are="" inadvertently="" encountered="" during="" operation="" in="" accordance="" with="" mmel="" provisions,="" procedures="" exist="" to="" instruct="" the="" flightcrew="" to="" exit="" the="" icing="" conditions="" immediately.="" the="" faa="" considers="" that="" those="" existing="" procedures="" will="" prevent="" conflict="" between="" the="" requirements="" of="" this="" ad="" and="" perceived="" problems="" regarding="" dispatch="" with="" inoperative="" boots.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" 15.="" request="" to="" consider="" differences="" in="" airplanes="" systems="" one="" commenter="" requests="" that="" the="" afm="" revision="" specified="" in="" paragraph="" (a)="" of="" the="" proposed="" rule="" be="" revised="" for="" those="" airplanes="" that="" are="" equipped="" with="" icing="" detection="" systems.="" such="" a="" revision="" should="" read="" ``activate="" the="" wing="" and="" tail="" leading="" edge="" pneumatic="" deicing="" boot="" system="" upon="" annunciation="" from="" an="" ice="" detector,''="" rather="" than="" ``at="" the="" first="" sign="" of="" ice="" anywhere="" on="" the="" aircraft,="" or="" upon="" annunciation="" from="" an="" ice="" detector="" system,="" whichever="" occurs="" first.''="" the="" commenter="" states="" that,="" since="" the="" sensor="" for="" the="" ice="" detection="" system="" detects="" ice="" buildup="" at="" the="" boot,="" it="" would="" make="" sense="" for="" airplanes="" that="" have="" an="" ice="" detection="" system="" to="" activate="" the="" boot="" only="" when="" ice="" is="" detected="" at="" the="" boot="" by="" the="" ice="" detection="" system.="" the="" commenter="" further="" points="" out="" that="" activating="" the="" boot="" when="" ice="" is="" not="" forming="" on="" the="" boot="" will="" not="" remove="" the="" ice="" formations="" elsewhere="" on="" the="" airplane,="" but="" will="" simply="" deteriorate="" the="" condition="" of="" the="" boot="" and="" provide="" no="" safety="" benefit.="" additionally,="" the="" commenter="" adds="" that="" if="" the="" ice="" detection="" system="" were="" inoperative="" for="" dispatch,="" it="" would="" be="" appropriate="" as="" a="" master="" minimum="" equipment="" list="" (mmel)="" condition="" to="" activate="" the="" boot="" at="" the="" first="" sign="" of="" icing.="" the="" faa="" does="" not="" concur="" that="" the="" final="" rule="" should="" be="" revised="" to="" address="" procedures="" specifically="" for="" airplanes="" equipped="" with="" icing="" detection="" systems.="" visual="" detection="" of="" icing="" by="" the="" flightcrew="" has="" been="" certificated="" as="" the="" primary="" means="" of="" ice="" detection.="" therefore,="" the="" faa="" has="" determined="" that,="" although="" ice="" detection="" systems="" may="" alert="" the="" flightcrew="" to="" the="" presence="" of="" icing,="" the="" flightcrew="" is="" still="" responsible="" to="" monitor="" the="" airframe="" for="" ice="" accretion.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" however,="" in="" the="" event="" a="" turbopropeller="" airplane="" equipped="" with="" pneumatic="" deicing="" boots="" was="" also="" equipped="" with="" an="" ice="" detection="" system="" that="" was="" approved="" as="" the="" primary="" ice="" detection="" system,="" the="" operator="" could="" request="" an="" alternative="" method="" of="" compliance="" in="" accordance="" with="" paragraph="" (b)="" of="" the="" final="" rule.="" 16.="" request="" to="" require="" additional="" operational="" procedures="" several="" commenters="" propose="" that="" the="" faa="" consider="" that="" minimum="" speed="" restrictions="" be="" used="" in="" conjunction="" with="" the="" early="" activation="" of="" the="" deicing="" boots.="" some="" of="" the="" commenters="" specify="" that="" these="" speed="" additions="" be="" applied="" during="" landing="" approach.="" one="" of="" the="" commenters="" expresses="" concern="" that="" various="" reports="" and="" research="" indicate="" that="" increasing="" the="" angle-of-attack="" with="" even="" a="" small="" ice="" formation="" on="" the="" airfoil="" can="" cause="" large="" increases="" in="" drag="" and="" loss="" of="" lift.="" the="" commenter="" contends="" that="" control="" of="" the="" angle-of-attack="" is="" critical="" in="" maintaining="" airfoil="" performance,="" and="" concludes="" that="" additional="" operational="" procedures="" must="" be="" added.="" the="" faa="" concurs="" that="" certain="" operational="" procedures="" may="" be="" beneficial="" when="" used="" with="" early="" activation="" of="" the="" deicing="" boots.="" as="" a="" complement="" to="" this="" ad,="" the="" faa="" is="" considering="" rulemaking="" regarding="" minimum="" speeds="" in="" icing="" conditions.="" as="" mentioned="" previously,="" the="" faa="" encourages="" manufacturers="" to="" present="" data="" via="" a="" request="" for="" approval="" of="" an="" alternative="" method="" of="" compliance="" to="" substantiate="" that="" their="" airplanes="" are="" either="" capable="" of="" flying="" safely="" with="" ice="" that="" accumulates="" prior="" to="" boot="" activation,="" or="" that="" they="" are="" not="" capable="" of="" flying="" safely="" but="" there="" are="" other="" means="" to="" address="" the="" unsafe="" condition.="" for="" example,="" in="" the="" case="" of="" cessna="" model="" 560="" series="" airplanes,="" the="" stall="" warning="" margins="" were="" modified="" to="" ensure="" the="" airplane="" could="" safely="" operate="" with="" ice="" accretions="" on="" the="" protected="" surfaces.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" 17.="" request="" to="" mandate="" installation="" of="" an="" ice="" detection="" system="" one="" commenter="" suggests="" that="" a="" required="" installation="" of="" a="" reliable="" ice="" detection="" system="" might="" alleviate="" the="" difficulties="" associated="" with="" flightcrew="" recognition="" of="" airfoil="" ice="" accretions.="" the="" commenter="" notes="" that,="" historically,="" the="" problem="" of="" ice="" detection="" has="" been="" the="" ability="" of="" the="" flightcrew="" to="" either="" identify="" that="" the="" airfoil="" has="" ice="" adhering="" to="" it="" or="" accurately="" determine="" that="" a="" certain="" thickness="" of="" ice="" exists="" on="" the="" airfoil="" prior="" to="" activation="" of="" the="" boot="" system.="" the="" faa="" concurs="" that="" installation="" of="" a="" reliable="" ice="" detection="" system="" would="" alleviate="" the="" difficulties="" associated="" with="" flightcrew="" recognition="" of="" airfoil="" ice="" accretions.="" this="" issue="" is="" being="" addressed="" by="" an="" arac="" working="" group.="" upon="" receipt="" of="" a="" recommendation="" from="" arac,="" the="" faa="" may="" consider="" further="" rulemaking.="" in="" the="" interim,="" the="" faa="" is="" issuing="" these="" airworthiness="" directives="" to="" impose="" a="" relatively="" simple="" deicing="" boot="" operational="" change="" to="" address="" the="" reduced="" handling="" qualities="" or="" controllability="" of="" the="" airplane="" due="" to="" ice="" accumulations="" on="" the="" protected="" surfaces.="" no="" change="" is="" necessary="" to="" the="" final="" rule="" in="" this="" regard.="" 18.="" request="" to="" require="" action="" to="" reduce="" adhesion="" characteristics="" one="" commenter="" requests="" that="" action="" be="" taken="" to="" minimize="" or="" reduce="" the="" ice="" adhesion="" characteristics="" of="" boot="" material.="" the="" commenter="" asserts="" that="" one="" reason="" flightcrews="" may="" be="" seeing="" large="" amounts="" of="" residual="" ice="" may="" be="" that,="" as="" the="" boot="" ages,="" the="" tendency="" for="" residual="" ice="" to="" stick="" to="" the="" boot="" surface="" may="" increase="" if="" the="" adhesion="" qualities="" of="" the="" boot="" materials="" are="" not="" properly="" maintained.="" in="" addition,="" the="" commenter="" suggests="" that="" the="" use="" of="" certain="" compounds="" (e.g.,="" icex,="" an="" ice-phobic="" chemical="" spray)="" can="" reduce="" ice="" adhesion="" by="" substantial="" margins.="" the="" faa="" does="" not="" concur="" with="" the="" commenter's="" request="" to="" require="" rulemaking="" to="" reduce="" adhesion="" characteristics="" of="" boot="" material.="" the="" faa="" considers="" that="" normal="" wear="" and="" tear="" on="" the="" deicing="" boot="" materials="" is="" to="" be="" expected,="" and="" the="" adhesion="" characteristics="" of="" the="" boot="" increases="" as="" the="" boot="" surface="" degrades="" over="" time.="" operators="" have="" the="" responsibility="" to="" monitor="" the="" performance="" of="" the="" deicing="" boots="" installed="" on="" their="" airplanes,="" and="" to="" perform="" maintenance="" as="" required.="" the="" faa="" acknowledges="" that="" use="" of="" certain="" ice-phobic="" chemicals="" may="" provide="" an="" additional="" safety="" benefit.="" however,="" a="" variety="" of="" factors="" (e.g.,="" normal="" wear="" and="" tear,="" ``patching,''="" and="" [[page="" 63583]]="" oxidation="" of="" boot="" material)="" exist="" in="" varying="" degrees="" on="" individual="" airplanes.="" as="" a="" result,="" the="" optimum="" frequency="" of="" application="" will="" vary="" during="" the="" life="" of="" the="" boot.="" the="" faa="" has="" received="" no="" quantitative="" data="" to="" demonstrate="" the="" adequacy="" of="" particular="" amounts="" of="" ice="" phobic="" chemical="" sprays="" or="" to="" provide="" adequate="" intervals="" of="" application.="" therefore,="" the="" faa="" cannot="" establish="" an="" appropriate="" application="" interval="" at="" this="" time.="" however,="" if="" additional="" data="" becomes="" available,="" the="" faa="" may="" consider="" further="" rulemaking.="" 19.="" request="" to="" consider="" the="" associated="" maintenance="" procedures="" and="" increased="" costs="" several="" commenters="" point="" out="" that="" certain="" maintenance="" requirements="" should="" be="" considered="" if="" the="" proposed="" afm="" revision="" is="" required.="" one="" commenter="" notes="" that="" a="" detailed="" review="" of="" maintenance="" procedures="" should="" be="" conducted="" regarding="" the="" deicing="" boots="" to="" ensure="" that,="" as="" the="" boot="" ages,="" the="" boot="" system="" continues="" to="" effectively="" shed="" ice.="" several="" commenters="" request="" that="" the="" faa="" also="" consider="" the="" additional="" costs="" that="" the="" proposed="" afm="" revision="" would="" require.="" one="" commenter="" states="" that="" the="" added="" cycling="" of="" the="" boots="" will="" require="" additional="" maintenance.="" the="" commenters="" express="" concern="" that="" the="" boots="" will="" wear="" out="" faster,="" need="" to="" be="" replaced="" at="" an="" accelerated="" rate,="" and="" thereby="" add="" additional="" costs.="" the="" faa="" acknowledges="" the="" concerns="" of="" these="" commenters.="" the="" faa="" considered="" the="" deicing="" boot="" fatigue="" issues="" surrounding="" the="" proposed="" ad,="" such="" as="" the="" reliability="" of="" the="" deicing="" boots.="" reliability="" of="" the="" deicing="" boots="" is="" affected="" by="" several="" factors,="" including:="" maintenance="" practices;="" abrasion="" during="" dry="" air,="" rain,="" hail,="" snow,="" and="" icing="" operations;="" oxidation;="" and,="" fatigue="" resulting="" from="" boot="" cycling.="" however,="" none="" of="" the="" commenters="" provided="" cost="" estimates="" for="" any="" of="" the="" maintenance="" costs="" or="" replacement="" costs.="" the="" faa="" did="" receive="" certain="" other="" information="" from="" a="" large="" operator="" of="" two="" airplane="" models="" that="" will="" be="" affected="" by="" this="" final="" rule.="" (one="" of="" the="" airplane="" models="" in="" that="" fleet="" currently="" observes="" the="" early-activation="" procedures="" required="" by="" this="" final="" rule="" and="" the="" other="" airplane="" model="" does="" not.)="" the="" operator="" stated="" that="" the="" largest="" contributor="" to="" periodic="" replacement="" of="" deicing="" boots="" on="" the="" fleet="" was="" erosion="" of="" the="" boot="" surface,="" rather="" than="" fatigue="" that="" would="" be="" caused="" by="" activation="" of="" deicing="" boots="" at="" the="" first="" sign="" of="" ice="" accretion.="" the="" faa="" recognizes="" that,="" in="" accomplishing="" the="" requirements="" of="" any="" ad,="" operators="" may="" incur="" ``incidental''="" costs="" in="" addition="" to="" the="" ``direct''="" costs="" that="" are="" reflected="" in="" the="" cost="" analysis="" presented="" in="" the="" ad="" preamble.="" however,="" the="" cost="" analysis="" in="" ad="" rulemaking="" actions="" typically="" does="" not="" include="" incidental="" costs.="" in="" the="" case="" of="" this="" ad,="" for="" example,="" the="" requirements="" are="" to="" revise="" the="" afm="" to="" include="" certain="" information.="" how="" operators="" actually="" ``implement''="" that="" information="" thereafter="" (once="" it="" is="" placed="" in="" the="" afm)="" may="" vary="" greatly="" among="" them:="" for="" some="" operators,="" implementation="" may="" necessitate="" extensive="" retraining="" among="" their="" flightcrews;="" for="" others,="" implementation="" may="" merely="" be="" considered="" a="" typical="" part="" of="" the="" routine,="" continuous="" training="" of="" their="" flightcrews.="" in="" light="" of="" this,="" it="" would="" be="" nearly="" impossible="" for="" the="" faa="" to="" calculate="" accurately="" or="" to="" reflect="" all="" costs="" associated="" with="" the="" afm="" revision="" required="" by="" this="" ad.="" the="" faa="" has="" determined="" that="" direct="" and="" incidental="" costs="" are="" still="" outweighed="" by="" the="" safety="" benefits="" of="" the="" ad.="" conclusion="" after="" careful="" review="" of="" the="" available="" data,="" including="" the="" comments="" noted="" above,="" the="" faa="" has="" determined="" that="" air="" safety="" and="" the="" public="" interest="" require="" the="" adoption="" of="" the="" rule="" with="" the="" changes="" described="" previously.="" the="" faa="" has="" determined="" that="" these="" changes="" will="" neither="" increase="" the="" economic="" burden="" on="" any="" operator="" nor="" increase="" the="" scope="" of="" the="" ad.="" cost="" impact="" there="" are="" approximately="" model="" g-73="" (mallard)="" and="" g-73t="" series="" airplanes="" of="" the="" affected="" design="" in="" the="" worldwide="" fleet.="" the="" faa="" estimates="" that="" 5="" airplanes="" of="" u.s.="" registry="" will="" be="" affected="" by="" this="" ad.="" it="" will="" take="" approximately="" 1="" work="" hour="" per="" airplane="" to="" accomplish="" the="" required="" afm="" revisions,="" at="" the="" average="" labor="" rate="" of="" $60="" per="" work="" hour.="" based="" on="" these="" figures,="" the="" cost="" impact="" of="" the="" ad="" on="" u.s.="" operators="" is="" estimated="" to="" be="" $300,="" or="" $60="" per="" airplane.="" the="" cost="" impact="" figure="" discussed="" above="" is="" based="" on="" assumptions="" that="" no="" operator="" has="" yet="" accomplished="" any="" of="" the="" requirements="" of="" this="" ad="" action,="" and="" that="" no="" operator="" would="" accomplish="" those="" actions="" in="" the="" future="" if="" this="" ad="" were="" not="" adopted.="" regulatory="" impact="" the="" regulations="" adopted="" herein="" will="" not="" have="" substantial="" direct="" effects="" on="" the="" states,="" on="" the="" relationship="" between="" the="" national="" government="" and="" the="" states,="" or="" on="" the="" distribution="" of="" power="" and="" responsibilities="" among="" the="" various="" levels="" of="" government.="" therefore,="" in="" accordance="" with="" executive="" order="" 12612,="" it="" is="" determined="" that="" this="" final="" rule="" does="" not="" have="" sufficient="" federalism="" implications="" to="" warrant="" the="" preparation="" of="" a="" federalism="" assessment.="" for="" the="" reasons="" discussed="" above,="" i="" certify="" that="" this="" action="" (1)="" is="" not="" a="" ``significant="" regulatory="" action''="" under="" executive="" order="" 12866;="" (2)="" is="" not="" a="" ``significant="" rule''="" under="" dot="" regulatory="" policies="" and="" procedures="" (44="" fr="" 11034,="" february="" 26,="" 1979);="" and="" (3)="" will="" not="" have="" a="" significant="" economic="" impact,="" positive="" or="" negative,="" on="" a="" substantial="" number="" of="" small="" entities="" under="" the="" criteria="" of="" the="" regulatory="" flexibility="" act.="" a="" final="" evaluation="" has="" been="" prepared="" for="" this="" action="" and="" it="" is="" contained="" in="" the="" rules="" docket.="" a="" copy="" of="" it="" may="" be="" obtained="" from="" the="" rules="" docket="" at="" the="" location="" provided="" under="" the="" caption="" addresses.="" list="" of="" subjects="" in="" 14="" cfr="" part="" 39="" air="" transportation,="" aircraft,="" aviation="" safety,="" safety.="" adoption="" of="" the="" amendment="" accordingly,="" pursuant="" to="" the="" authority="" delegated="" to="" me="" by="" the="" administrator,="" the="" federal="" aviation="" administration="" amends="" part="" 39="" of="" the="" federal="" aviation="" regulations="" (14="" cfr="" part="" 39)="" as="" follows:="" part="" 39--airworthiness="" directives="" 1.="" the="" authority="" citation="" for="" part="" 39="" continues="" to="" read="" as="" follows:="" authority:="" 49="" u.s.c.="" 106(g),="" 40113,="" 44701.="" sec.="" 39.13="" [amended]="" 2.="" section="" 39.13="" is="" amended="" by="" adding="" the="" following="" new="" airworthiness="" directive:="" 99-19-07="" gulfstream="" american="" (frakes="" aviation):="" amendment="" 39-11296.="" docket="" 99-nm-141-ad.="" applicability:="" model="" g-73="" (mallard)="" and="" g-73t="" series="" airplanes="" equipped="" with="" pneumatic="" deicing="" boots,="" certificated="" in="" any="" category.="" compliance:="" required="" as="" indicated,="" unless="" accomplished="" previously.="" to="" ensure="" that="" flightcrews="" activate="" the="" wing="" and="" tail="" pneumatic="" deicing="" boots="" at="" the="" first="" signs="" of="" ice="" accumulation="" on="" the="" airplane,="" accomplish="" the="" following:="" (a)="" within="" 10="" days="" after="" the="" effective="" date="" of="" this="" ad:="" revise="" the="" limitations="" section="" of="" the="" faa-approved="" airplane="" flight="" manual="" (afm)="" to="" include="" the="" following="" requirements="" for="" activation="" of="" the="" ice="" protection="" systems.="" this="" may="" be="" accomplished="" by="" inserting="" a="" copy="" of="" this="" ad="" in="" the="" afm.=""> Except if the AFM otherwise specifies that deicing
boots should not be used for certain phases of flight (e.g., take-
off, final approach, and landing), compliance with the following is
required.
Wing and Tail Leading Edge Pneumatic Deicing Boot
System, if installed, must be activated:
[[Page 63584]]
--At the first sign of ice formation anywhere on the aircraft, or
upon annunciation from an ice detector system, whichever occurs
first; and
--The system must either be continued to be operated in the
automatic cycling mode, if available; or the system must be manually
cycled as needed to minimize the ice accretions on the airframe.
The wing and tail leading edge pneumatic deicing boot
system may be deactivated only after completion of an entire deicing
cycle after leaving icing conditions.
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Airplane Certification Office, ASW-
150, FAA, Rotorcraft Directorate. The request shall be forwarded
through an appropriate FAA Operations Inspector, who may add
comments and then send it to the Manager, Airplane Certification
Office, ASW-150 ACO.
Note 1: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Airplane Certification Office, ASW-150 ACO.
(c) Special flight permits may be issued in accordance with
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR
21.197 and 21.199) to operate the airplane to a location where the
requirements of this AD can be accomplished.
(d) This amendment becomes effective on December 27, 1999.
Issued in Renton, Washington, on November 10, 1999.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-30133 Filed 11-19-99; 8:45 am]
BILLING CODE 4910-13-U
