[Federal Register Volume 63, Number 187 (Monday, September 28, 1998)]
[Rules and Regulations]
[Pages 51520-51525]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-25774]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-CE-57-AD; Amendment 39-10801; AD 98-20-34]
RIN 2120-AA64
Airworthiness Directives; Twin Commander Aircraft Corporation
Models 500, 500-A, 500-B, 500-S, 500-U, 520, 560, 560-A, 560-E, 560-F,
680, 680-E, 680FL(P), 680T, 680V, 680W, 681, 685, 690, 690A, 690B,
690C, 690D, 695, 695A, 695B, and 720 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
applies to Twin Commander Aircraft Corporation Models 500, 500-A, 500-
B, 500-S, 500-U, 520, 560, 560-A, 560-E, 560-F, 680, 680-E, 680FL(P),
680T, 680V, 680W, 681, 685, 690, 690A, 690B, 690C, 690D, 695, 695A,
695B, and 720 airplanes. This action requires revising the FAA-approved
Airplane Flight Manual (AFM) to specify procedures that would prohibit
flight in severe icing conditions (as determined by certain visual
cues), limit or prohibit the use of various flight control devices
while in severe icing conditions, and provide the flight crew with
recognition cues for, and procedures for exiting from, severe icing
conditions. This AD is prompted by the results of a review of the
requirements for certification of these airplanes in icing conditions,
new information on the icing environment, and icing data provided
currently to the flight crew. The actions specified by this AD are
intended to minimize the potential hazards associated with operating
these airplanes in severe icing conditions by providing more clearly
defined procedures and limitations associated with such conditions.
EFFECTIVE DATE: November 3, 1998.
ADDRESSES: This information may be examined at the Federal Aviation
Administration (FAA), Central Region, Office of the Regional Counsel,
Attention: Rules Docket No. 97-CE-57-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106.
FOR FURTHER INFORMATION CONTACT: Mr. John P. Dow, Sr., Aerospace
Engineer, Small Airplane Directorate, Aircraft Certification Service,
1201 Walnut, suite 900, Kansas City, Missouri 64106, telephone (816)
426-6932, facsimile (816) 426-2169.
SUPPLEMENTARY INFORMATION:
Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14
CFR part 39) to include an AD that would apply to Twin Commander
Aircraft Corporation Models 500, 500-A, 500-B, 500-S, 500-U, 520, 560,
560-A, 560-E, 560-F, 680, 680-E, 680FL(P), 680T, 680V, 680W, 681, 685,
690, 690A, 690B, 690C, 690D, 695, 695A, 695B, and 720 airplanes was
published in the Federal Register on September 16, 1997 (62 FR 48549).
The action proposed to require revising the Limitations Section of the
FAA-approved Airplane Flight Manual (AFM) to specify procedures that
would:
[[Page 51521]]
require flight crews to immediately request priority
handling from Air Traffic Control to exit severe icing conditions (as
determined by certain visual cues);
prohibit flight in severe icing conditions (as determined
by certain visual cues);
prohibit use of the autopilot when ice is formed aft of
the protected surfaces of the wing, or when an unusual lateral trim
condition exists; and
require that all icing wing inspection lights be operative
prior to flight into known or forecast icing conditions at night.
That action also proposed to require revising the Normal Procedures
Section of the FAA-approved AFM to specify procedures that would:
limit the use of the flaps and prohibit the use of the
autopilot when ice is observed forming aft of the protected surfaces of
the wing, or if unusual lateral trim requirements or autopilot trim
warnings are encountered; and
provide the flight crew with recognition cues for, and
procedures for exiting from, severe icing conditions.
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.
In addition to the proposed rule described previously, in September
1997, the FAA issued 24 other similar proposals that address the
subject unsafe condition on various airplane models (see below for a
listing of all 24 proposed rules). These 24 proposals also were
published in the Federal Register on September 16, 1997. This final
rule contains the FAA's responses to all public comments received for
each of these proposed rules.
------------------------------------------------------------------------
Manufacturer/Airplane Federal Register
Docket No. model citation
------------------------------------------------------------------------
97-CE-49-AD................... Aerospace 62 FR 48520
Technologies of
Australia, Models
N22B and N24A.
97-CE-50-AD................... Harbin Aircraft Mfg. 62 FR 48513
Corporation Model
Y12 IV.
97-CE-51-AD................... Partenavia 62 FR 48524
Costruzioni
Aeronauticas, S.p.A.
Models, P68, AP68TP
300, AP68TP 600.
97-CE-52-AD................... Industrie 62 FR 48502
Aeronautiche
Meccaniche Rinaldo
Piaggio S.p.A. Model
P-180.
97-CE-53-AD................... Pilatus Aircraft Ltd. 62 FR 48499
Models PC-12 and PC-
12/45.
97-CE-54-AD................... Pilatus Britten- 62 FR 48538
Norman Ltd., Models
BN-2A, BN-2B, and BN-
2T.
97-CE-55-AD................... SOCATA--Groupe 62 FR 48506
Aerospatiale Model
TBM-700.
97-CE-56-AD................... Aerostar Aircraft 62 FR 48481
Corporation Models
PA-60-600, -601, -
601P, -602P, and -
700P.
97-CE-57-AD................... Twin Commander 62 FR 48549
Aircraft Corporation
Models 500, -500-A, -
500-B,-500-S, -500-
U, -520, -560, -560-
A, -560-E, -560-F, -
680, -680-E, -
680FL(P), -680T, -
680V, -680W, -681,-
685, -690, -690A, -
690B, -690C, -690D, -
695, -695A, -695B,
and 720.
97-CE-58-AD................... Raytheon Aircraft 62 FR 48517
Company Models E55,
E55A, 58, 58A, 58P,
58PA, 58TC, 58TCA,
60 series, 65-B80
series, 65-B90
series, 90 series,
F90 series, 100
series, 300 series,
and B300 series.
97-CE-59-AD................... Raytheon Aircraft 62 FR 48531
Company Model 2000..
97-CE-60-AD................... The New Piper 62 FR 48542
Aircraft, Inc.
Models PA-46-310P
and PA-46-350P.
97-CE-61-AD................... The New Piper 62 FR 48546
Aircraft, Inc.
Models PA-23, PA-23-
160, PA-23-235, PA-
23-250, PA-E23-250,
PA-30, PA-39, PA-40,
PA-31, PA-31-300, PA-
31-325, PA-31-350,
PA-34-200, PA-34-
200T, PA-34-220T, PA-
42, PA-42-720, PA-42-
1000.
97-CE-62-AD................... Cessna Aircraft 62 FR 48535
Company Models
P210N, T210N, P210R,
and 337 series.
97-CE-63-AD................... Cessna Aircraft 62 FR 48528
Company Models T303,
310R, T310R, 335,
340A, 402B, 402C,
404, F406, 414,
414A, 421B, 421C,
425, and 441.
97-CE-64-AD................... SIAI-Marchetti S.r.I. 62 FR 48510
(Augusta) Models
SF600 and SF600A.
97-NM-170-AD.................. Cessna Aircraft 62 FR 48560
Company Models 500,
501, 550, 551, and
560 series.
97-NM-171-AD.................. Sabreliner 62 FR 48556
Corporation Models
40, 60, 70, and 80
series.
97-NM-172-AD.................. Gulfstream Aerospace 62 FR 48563
Model G-159 series.
97-NM-173-AD.................. McDonnell Douglas 62 FR 48553
Models DC-3 and DC-4
series.
97-NM-174-AD.................. Mitsubishi Heavy 62 FR 48567
Industries Model YS-
11 and YS-11A series.
97-NM-175-AD.................. Frakes Aviation Model 62 FR 48577
G-73 (Mallard) and G-
73T series.
97-NM-176-AD.................. Fairchild Models F27 62 FR 48570
and FH227 series.
97-NM-177-AD.................. Lockheed L-14 and L- 62 FR 48574
18 series airplanes.
------------------------------------------------------------------------
Comment 1. Unsubstantiated Unsafe Condition for This Model
One commenter suggests that the AD's were developed in response to
a suspected contributing factor of an accident involving an airplane
type unrelated to the airplanes specified in the proposal. The
commenter states that these proposals do not justify that an unsafe
condition exists or could develop in a product of the same type design.
Therefore, the commenter asserts that the proposal does not meet the
criteria for the issuance of an AD as specified 14 CFR part 39
(Airworthiness Directives) of the Federal Aviation Regulations.
The FAA does not concur. As stated in the notice of proposed
rulemaking (NPRM), the FAA has identified an unsafe condition
associated with operating the airplane in severe icing conditions. As
stated in the preamble to the proposal, the FAA has not required that
airplanes be shown to be capable of operating safely in icing
conditions outside the certification envelope specified in Appendix C
of part 25 of the Federal Aviation Regulations (14 CFR part 25). This
means that any time an airplane is flown in icing conditions for which
it is not certificated, there is a potential for an unsafe condition to
exist or develop and the flight crew must take steps to exit those
conditions expeditiously. Further, the FAA has determined that flight
crews are not currently provided with adequate information necessary to
determine when an airplane is operating in icing conditions for which
it is not certificated or what action to take when such conditions are
encountered. The absence of this information presents an
[[Page 51522]]
unsafe condition because without that information, a pilot may remain
in potentially hazardous icing conditions. This AD addresses the unsafe
condition by requiring AFM revisions that provide the flight crews with
visual cues to determine when icing conditions have been encountered
for which the airplane is not certificated, and by providing procedures
to safely exit those conditions.
Further, in the preamble of the proposed rule, the FAA discussed
the investigation of roll control anomalies to explain that this
investigation was not a complete certification program. The testing was
designed to examine only the roll handling characteristics of the
airplane in certain droplets the size of freezing drizzle. The testing
was not a certification test to approve the airplane for flight into
freezing drizzle. The results of the tests were not used to determine
if this AD is necessary, but rather to determine if design changes were
needed to prevent a catastrophic roll upset. The roll control testing
and the AD are two unrelated actions.
Additionally, in the preamble of the proposed rule, the FAA
acknowledged that the flight crew of any airplane that is certificated
for flight in icing conditions may not have adequate information
concerning flight in icing conditions outside the icing envelope.
However, in 1996, the FAA found that the specified unsafe condition
must be addressed as a higher priority on airplanes equipped with
pneumatic deicing boots and unpowered roll control systems. These
airplanes were addressed first because the flight crew of an airplane
having an unpowered roll control system must rely solely on physical
strength to counteract roll control anomalies, whereas a roll control
anomaly that occurs on an airplane having a powered roll control system
need not be offset directly by the flight crew. The FAA also placed a
priority on airplanes that are used in regularly scheduled passenger
service. The FAA has previously issued AD's to address those airplanes.
Since the issuance of those AD's, the FAA has determined that similar
AD's should be issued for similarly equipped airplanes that are not
used in regularly scheduled passenger service.
Comment 2. AD is Inappropriate to Address Improper Operation of the
Airplane
One commenter requests that the proposed AD be withdrawn because an
unsafe condition does not exist within the airplane. Rather, the
commenter asserts that the unsafe condition is the improper operation
of the airplane. The commenter further asserts that issuance of an AD
is an inappropriate method to address improper operation of the
airplane.
The FAA does not concur. The FAA has determined that an unsafe
condition does exist as explained in the proposed notice and discussed
previously. As specifically addressed in Amendment 39-106 of part 39 of
the Federal Aviation Regulations (14 CFR part 39), the responsibilities
placed on the FAA statute (49 U.S.C. 40101, formerly the Federal
Aviation Act) justify allowing AD's to be issued for unsafe conditions
however and wherever found, regardless of whether the unsafe condition
results from maintenance, design defect, or any other reason.
This same commenter considers part 91 (rather than part 39) of the
Federal Aviation Regulations (14 CFR part 91) the appropriate
regulation to address the problems of icing encounters outside of the
limits for which the airplane is certificated. Therefore, the commenter
requests that the FAA withdraw the proposal.
The FAA does not concur. Service experience demonstrates that
flight in icing conditions that is outside the icing certification
envelope does occur. Apart from the visual cues provided in these final
rules, there is no existing method provided to the flight crews to
identify when the airplane is in a condition that exceeds the icing
certification envelope. Because this lack of awareness may create an
unsafe condition, the FAA has determined that it is appropriate to
issue an AD to require a revision of the AFM to provide this
information.
One commenter asserts that while it is prudent to advise and
routinely remind the pilots about the hazards associated with flight
into known or forecast icing conditions, the commenter is opposed to
the use of an AD to accomplish that function. The commenter states that
pilots' initial and bi-annual flight checks are the appropriate
vehicles for advising the pilots of such hazards, and that such
information should be integrated into the training syllabus for all
pilot training.
The FAA does not concur that substituting advisory material and
mandatory training for issuance of an AD is appropriate. 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 such
advisory materials and training alone are not adequate to address the
unsafe condition. The only method of ensuring that certain information
is available to the pilot is through incorporation of the information
into the Limitations Section of the AFM. The appropriate vehicle for
requiring such a revision of the AFM is issuance of an AD. No change is
necessary to the final rule.
Comment 3. Inadequate Visual Cues
One commenter provides qualified support for the AD. The commenter
notes that the recent proposals are identical to the AD's issued about
a year ago. Although the commenter supports the intent of the AD's as
being appropriate and necessary, the commenter states that it is
unfortunate that the flight crew is burdened with recognizing icing
conditions with visual cues that are inadequate to determine certain
icing conditions. The commenter points out that, for instance, side
window icing (a very specific visual cue) was determined to be a valid
visual cue during a series of icing tanker tests on a specific
airplane; however, later testing of other models of turboprop airplanes
revealed that side window icing was invalid as a visual cue for
identifying icing conditions outside the scope of Appendix C.
The FAA does not concur with the commenters' request to provide
more specific visual cues. The FAA finds that the value of visual cues
has been substantiated during in-service experience. Additionally, the
FAA finds that the combined use of the generic cues provided and the
effect of the final rules in increasing the awareness of pilots
concerning the hazard of operating outside of the certification icing
envelope will provide an acceptable level of safety. Although all of
the cues may not be exhibited on a particular model, the FAA considers
that at least some of the cues will be exhibited on all of the models
affected by this AD. For example, some airplanes may not have side
window cues in freezing drizzle, but would exhibit other cues (such as
accumulation of ice aft of the protected area) under those conditions.
For these reasons, the FAA considers that no changes regarding visual
cues are necessary in the final rule. However, for those operators that
elect to identify airplane-specific visual cures, the FAA would
consider a request for approval of an alternative method of compliance,
in accordance with the provisions of this AD.
Comment 4. Request for Research and Use of Wing-Mounted Ice Detectors
One commenter requests that wing-mounted ice detectors, which
provide real-time icing severity information (or immediate feedback) to
flight crews, continue to be researched and used
[[Page 51523]]
throughout the fleet. The FAA infers from this commenter's request that
the commenter asks that installation of these ice detectors be mandated
by the FAA.
While the FAA supports the development of such ice detectors, the
FAA does not concur that installation of these ice detectors should be
required at this time. Visual cues are adequate to provide an
acceptable level of safety; therefore, mandatory installation of ice
detector systems, in this case, is not necessary to address the unsafe
condition. Nevertheless, because such systems may improve the current
level of safety, the FAA has officially tasked the Aviation Rulemaking
Advisory Committee (ARAC) to develop a recommendation concerning ice
detection. Once the ARAC has submitted its recommendation, the FAA may
consider further rulemaking action to require installation of such
equipment.
Comment 5. Particular Types of Icing
This same commenter also requests that additional information be
included in paragraph (a) of the AD that would specify particular types
of icing or particular accretions that result from operating in
freezing precipitation. The commenter asserts that this information is
of significant value to the flightcrew.
The FAA does not concur with the commenter's suggestion to specify
types of icing or accretion. The FAA has determined that supercooled
large droplets (SLD) can result in rime ice, mixed (intermediate) ice,
and ice with glaze or clear appearance. Therefore, the FAA finds that
no type of icing can be excluded from consideration during operations
in freezing precipitation, and considers it unnecessary to cite those
types of icing in the AD.
Comment 6. Restrictions on Use of Autopilot Could Have Adverse Impact
One commenter specifically addressed the Twin Commander 690 series
airplanes. This commenter stated that the restriction against use of
the autopilot in certain conditions of severe icing would have an
adverse impact on certain 14 CFR part 135 single-pilot IFR operations,
and thus should be revised to provide only information. Further the
commenter stated it is counterproductive to and does not materially
contribute to the safety of flight.
The FAA does not concur. Federal Aviation Regulation, part 135 (14
CFR part 135, section 135.103), ``Exceptions to second in command
requirements: IFR operations'', addresses weather conditions that must
exist in order to operate without a second in command. Federal Aviation
Regulations part 135 (14 CFR part 135, section 135.105): ``Exception
for second in command requirements: Approval for use of autopilot
systems'', addresses certain conditions that have to be met in order to
rely upon an autopilot in lieu of a second in command.
The regulation only specifies the installation of a functioning and
operable autopilot that meets the operations specifications. The pilot-
in-charge determines the appropriate use of the autopilot, unless
mandated by other regulation, i.e., airworthiness directive. In the
case of the proposed AD, the autopilot could not be used in certain
conditions of severe icing. The autopilot would still be operable and
would meet the operations specifications, and could then be utilized
once the pilot-in-charge exited these severe icing conditions.
The regulations do not address icing conditions, and the AD does
not revise or amend the above referenced sections of 14 CFR part 135.
Therefore, as long as the airplane meets all the autopilot restrictions
of 14 CFR 135.105 and the weather requirements of 14 CFR 135.103 are
met, restricting use of the autopilot in certain icing conditions would
not contradict the current regulations.
Additionally, the FAA does not concur with the commenter's
statement that the masked symptoms caused by the use of autopilot in
severe icing is a ``hunch''. The FAA has carefully examined data from
aircraft types involved in various modes of upset in icing conditions.
This data includes flight data recorder information obtained from
revenue flights, flight test instrumentation, radar data, interviews
with flight test pilots and review of anecdotal information on multi-
engine airplanes, including the Commander 690 series airplanes.
This examination shows a reduction of aircraft control or
performance is imminent and upset may occur with continued flight in
severe icing conditions, and in certain infrequent cases of icing
conditions within the design limits. This upset may occur without
substantial natural or artificial warning in advance of aerodynamic
stall, and at higher speed than without ice contamination. In these
cases, there is clear and compelling evidence of three important
benefits that arise from hand flying the airplane.
Benefit one is prevention. The pilot is usually able to feel the
onset of adverse changes to the handling characteristics of the
airplane by changes in the way the airplane responds to control input.
Essentially, the airplane ``feel'' is different. The different ``feel''
or handling characteristics should alert the pilot that an immediate
decrease in angle-of-attack, change in course, or altitude is needed to
prevent possible upset. Some of these handling characteristics could be
increased or decreased force to change the control surface position,
vibration or buffeting of the control surface, or greater control
surface deflection to obtain the desired airplane response.
Benefit two is reducing the severity of an upset. By disconnecting
the autopilot early in a potential upset sequence, extreme trim inputs
will be prevented. Delayed disconnect of the autopilot could increase
the potential for cross trimmed flight controls at aerodynamic stall
(most likely at higher than normal airspeeds), and may lead to a spiral
spin entry, or unusual attitude. In past incidents, autopilot trim
inputs reached trim surface limits prior to aerodynamic stall,
complicating recovery by resulting in higher control forces that the
pilot had to apply.
Benefit three is the potential for faster recovery. With ``hands-
on'' the controls, the pilot is able to recover immediately should an
upset occur. It is important to remember that the response
characteristics of an ice contaminated airplane may differ dramatically
from that of the uncontaminated airplane. Severe icing implies even
more adverse changes than tested within normal icing conditions. This
final rule will not change as a result of this comment.
The FAA's Determination
After careful review of all available information related to the
subject presented above, the FAA has determined that air safety and the
public interest require the adoption of the rule as proposed except for
minor editorial corrections. The FAA has determined that these minor
corrections will not change the meaning of the AD and will not add any
additional burden upon the public than was already proposed.
Cost Impact
The FAA estimates that 811 airplanes in the U.S. registry will be
affected by this AD, that it will take approximately 1 workhour per
airplane to accomplish this action, and that the average labor rate is
approximately $60 an hour. Since an owner/operator who holds at least a
private pilot's certificate as authorized by sections 43.7 and 43.9 of
the Federal Aviation Regulations (14 CFR 43.7 and 43.9) can accomplish
this action, the only cost impact upon the public is the time it will
take the affected airplane
[[Page 51524]]
owners/operators to incorporate this AFM revision.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of this requirements of this AD
action, and that no operator will accomplish those actions in the
future if this AD were not adopted.
In addition, the FAA recognizes that this action may impose
operational costs. However, these costs are incalculable because the
frequency of occurrence of the specified conditions and the associated
additional flight time cannot be determined. Nevertheless, because of
the severity of the unsafe condition, the FAA has determined that
continued operational safety necessitates the imposition of the costs.
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 copy of the final evaluation prepared for this
action is contained in the Rules Docket. A copy of it may be obtained
by contacting 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 a new airworthiness directive
(AD) to read as follows:
98-20-34 Twin Commander Aircraft Corporation: Amendment 39-10801;
Docket No. 97-CE-57-AD.
Applicability: Models 500, -500-A, -500-B, -500-S, -500-U, -520,
-560, -560-A, -560-E, -560-F, -680, -680-E, -680FL(P), -680T, -680V,
-680W, -681, -685, -690, -690A, -690B, 690C, -690D, -695, -695A, -
695B, and 720 airplanes (all serial numbers), certificated in any
category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (d) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless already accomplished.
To minimize the potential hazards associated with operating the
airplane in severe icing conditions by providing more clearly
defined procedures and limitations associated with such conditions,
accomplish the following:
(a) Within 30 days after the effective date of this AD,
accomplish the requirements of paragraphs (a)(1) and (a)(2) of this
AD.
Note 2: Operators should initiate action to notify and ensure
that flight crewmembers are apprised of this change.
(1) Revise the FAA-approved Airplane Flight Manual (AFM) by
incorporating the following into the Limitations Section of the AFM.
This may be accomplished by inserting a copy of this AD in the AFM.
``WARNING
Severe icing may result from environmental conditions outside of
those for which the airplane is certificated. Flight in freezing
rain, freezing drizzle, or mixed icing conditions (supercooled
liquid water and ice crystals) may result in ice build-up on
protected surfaces exceeding the capability of the ice protection
system, or may result in ice forming aft of the protected surfaces.
This ice may not be shed using the ice protection systems, and may
seriously degrade the performance and controllability of the
airplane.
During flight, severe icing conditions that exceed
those for which the airplane is certificated shall be determined by
the following visual cues. If one or more of these visual cues
exists, immediately request priority handling from Air Traffic
Control to facilitate a route or an altitude change to exit the
icing conditions.
Unusually extensive ice accumulation on the airframe and
windshield in areas not normally observed to collect ice.
Accumulation of ice on the lower surface of the wing aft of
the protected area.
Accumulation of ice on the engine nacelles and propeller
spinners farther aft than normally observed.
Since the autopilot, when installed and operating, may
mask tactile cues that indicate adverse changes in handling
characteristics, use of the autopilot is prohibited when any of the
visual cues specified above exist, or when unusual lateral trim
requirements or autopilot trim warnings are encountered while the
airplane is in icing conditions.
All wing icing inspection lights must be operative
prior to flight into known or forecast icing conditions at night.
[Note: This supersedes any relief provided by the Master Minimum
Equipment List (MMEL).]''
(2) Revise the FAA-approved AFM by incorporating the following
into the Normal Procedures Section of the AFM. This may be
accomplished by inserting a copy of this AD in the AFM.
``THE FOLLOWING WEATHER CONDITIONS MAY BE CONDUCIVE TO SEVERE IN-FLIGHT
ICING
Visible rain at temperatures below 0 degrees Celsius
ambient air temperature.
Droplets that splash or splatter on impact at
temperatures below 0 degrees Celsius ambient air temperature.
PROCEDURES FOR EXITING THE SEVERE ICING ENVIRONMENT
These procedures are applicable to all flight phases from
takeoff to landing. Monitor the ambient air temperature. While
severe icing may form at temperatures as cold as -18 degrees
Celsius, increased vigilance is warranted at temperatures around
freezing with visible moisture present. If the visual cues specified
in the Limitations Section of the AFM for identifying severe icing
conditions are observed, accomplish the following:
Immediately request priority handling from Air Traffic
Control to facilitate a route or an altitude change to exit the
severe icing conditions in order to avoid extended exposure to
flight conditions more severe than those for which the airplane has
been certificated.
Avoid abrupt and excessive maneuvering that may
exacerbate control difficulties.
Do not engage the autopilot.
If the autopilot is engaged, hold the control wheel
firmly and disengage the autopilot.
If an unusual roll response or uncommanded roll control
movement is observed, reduce the angle-of-attack.
Do not extend flaps when holding in icing conditions.
Operation with flaps extended can result in a reduced wing angle-of-
attack, with the possibility of ice forming on the upper surface
further aft on the wing than normal, possibly aft of the protected
area.
If the flaps are extended, do not retract them until
the airframe is clear of ice.
[[Page 51525]]
Report these weather conditions to Air Traffic
Control.''
(b) Incorporating the AFM revisions, as required by this AD, may
be performed by the owner/operator holding at least a private pilot
certificate as authorized by section 43.7 of the Federal Aviation
Regulations (14 CFR 43.7), and must be entered into the aircraft
records showing compliance with this AD in accordance with section
43.9 of the Federal Aviation Regulations (14 CFR 43.9).
(c) Special flight permits may be issued in accordance with
sections 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) An alternative method of compliance or adjustment of the
compliance time that provides an equivalent level of safety may be
approved by the Manager, Small Airplane Directorate, FAA, 1201
Walnut, suite 900, Kansas City, Missouri 64106. The request shall be
forwarded through an appropriate FAA Maintenance Inspector, who may
add comments and then send it to the Manager, Small Airplane
Directorate.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Small Airplane Directorate.
(e) All persons affected by this directive may examine
information related to this AD at the FAA, Central Region, Office of
the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City,
Missouri 64106.
(f) This amendment becomes effective on November 3, 1998.
Issued in Kansas City, Missouri, on September 18, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-25774 Filed 9-25-98; 8:45 am]
BILLING CODE 4910-13-P
