[Federal Register Volume 64, Number 193 (Wednesday, October 6, 1999)]
[Proposed Rules]
[Pages 54239-54240]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26086]
[[Page 54239]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-226-AD]
RIN 2120-AA64
Airworthiness Directives; Short Brothers Model SD3-60 SHERPA,
SD3-SHERPA, SD3-30, and SD3-60 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to all Short Brothers Model SD3-60
SHERPA, SD3-SHERPA, SD3-30, and SD3-60 series airplanes. This proposal
would require replacement of the existing pneumatic de-icing boot
pressure indicator switch with a newly designed switch. This proposal
is prompted by an occurrence on a similar airplane model in which the
pneumatic de-icing boot indication light may have provided the
flightcrew with misleading information as to the proper functioning of
the de-icing boots. The actions specified by the proposed AD are
intended to prevent ice accumulation on the airplane leading edges,
which could reduce controllability of the airplane.
DATES: Comments must be received by November 5, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-226-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except
Federal holidays.
Information concerning this proposal may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
227-2110; fax (425) 227-1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NM-226-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules
Docket No. 99-NM-226-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On December 26, 1989, a British Aerospace Jetstream Model BA-3101
series airplane impacted the ground approximately 400 feet short of the
runway while executing an instrument landing system (ILS) approach. The
accident occurred at the Tri-Cities Airport, Pasco, Washington. The
National Transportation Safety Board (NTSB) determined that the
probable cause of the accident was the flightcrew's decision to
continue an unstabilized ILS approach that led to a stall, most likely
of the horizontal stabilizer, and loss of control at low altitude.
Contributing to the stall and loss of control was the accumulation of
leading edge ice, which degraded the aerodynamic performance of the
airplane.
One result of the NTSB investigation was the determination that the
flight deck wing de-icing light illuminated at a lower pressure than
the pressure required to fully inflate the de-icing boots. The
premature illumination of the wing de-icing light was due to a failure
within the wing de-icing boot system, which allowed sufficient air
pressure to give the appearance of normal operation based on the de-
icing light, without actually inflating the boots sufficiently to
remove ice.
Based on an NTSB Safety Recommendation, the FAA reviewed the
pneumatic de-icing boot system designs for airplanes operated under
parts 121 and 135 of the Federal Aviation Regulations to ensure that
the pneumatic pressure threshold at which each de-icing boot indication
light is designed to illuminate is sufficient pressure for effective
operation of the pneumatic de-icing boots. The FAA has determined that
the flight deck pneumatic de-icing boot pressure indicator switch on
all Short Brothers Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60
series airplanes may allow the flight deck indication light to
illuminate at a lower pressure [10 pounds per square inch gage (psig)]
than the pressure required to fully inflate the de-icing boots (15
psig). This condition, if not corrected, could result in ice
accumulation on the airplane leading edges, which could reduce
controllability of the airplane.
FAA's Conclusions
These airplane models are manufactured in the United Kingdom and
are type certificated for operation in the United States under the
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR
21.29) and the applicable bilateral airworthiness agreement. The FAA
has determined that AD action is necessary for products of this type
design that are certificated for operation in the United States.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design registered
in the United States, the proposed AD would require that the existing
pneumatic de-icing boot pressure indicator switch be replaced with a
switch that activates the indicator light at 15 psig. The action would
be required in accordance with a method approved by the FAA.
Cost Impact
The FAA estimates that 89 airplanes of U.S. registry would be
affected by this proposed AD. Since the manufacturer has not yet
developed one specific modification commensurate with the requirements
of this proposal, the FAA is unable at this time to provide specific
information as to the number of work hours or cost of parts that would
be
[[Page 54240]]
required to accomplish the proposed modification. As indicated earlier
in this preamble, the FAA specifically invites the submission of
comments and other data regarding the economic aspect of this proposal.
Regulatory Impact
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, 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 draft
regulatory 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.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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:
Short Brothers PLC: Docket 99-NM-226-AD.
Applicability: All Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and
SD3-60 series airplanes; 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 (b) 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 accomplished
previously.
To prevent ice accumulation on the airplane leading edges, which
could reduce controllability of the airplane, accomplish the
following:
Modification
(a) Within 1 year after the effective date of this AD, replace
the flight deck pneumatic de-icing boot pressure indicator switch
with a switch that activates the flight deck indicator light at 15
pounds per square inch gage, in accordance with a method approved by
the Manager, International Branch, ANM-116, FAA, Transport Airplane
Directorate.
Alternative Methods of Compliance
(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, International Branch, ANM-116.
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, International Branch, ANM-116.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the International Branch, ANM-116.
Special Flight Permits
(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.
Issued in Renton, Washington, on September 30, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-26086 Filed 10-5-99; 8:45 am]
BILLING CODE 4910-13-P
