[Federal Register Volume 59, Number 243 (Tuesday, December 20, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31182]


[[Page Unknown]]

[Federal Register: December 20, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-168-AD]

 

Airworthiness Directives; Jetstream Model ATP Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Jetstream Model ATP 
airplanes. This proposal would require installation of modified engine 
de-ice timers, modification of the electrical wiring for the duct heat 
of the engine air intake, and installation of a time delay for the de-
ice system in the air intake duct of the right engine. This proposal 
would also require associated revisions to the Airplane Flight Manual. 
This proposal is prompted by reports of ice that accreted in the engine 
air intake ducts and was ingested into the engine; this resulted in 
engine power rollback (loss of engine power). The actions specified by 
the proposed AD are intended to prevent loss of multiple engine power 
during flight in icing conditions.

DATES: Comments must be received by January 31, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-168-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.
    The service information referenced in the proposed rule may be 
obtained from Jetstream Aircraft, Inc., P.O. Box 16029, Dulles 
International Airport, Washington, DC 20041-6029. This information may 
be examined at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2148; fax (206) 227-1320.

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 94-NM-168-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-103, Attention: Rules 
Docket No. 94-NM-168-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, recently notified the FAA that an 
unsafe condition may exist on certain Jetstream Model ATP airplanes. 
The CAA advises that probable ingestion of accreted ice, shed from the 
inner surfaces of the engine air intake ducts, has resulted in engine 
power rollbacks (loss of engine power) during flight in icing 
conditions. Five reports have been received: three reports of power 
rollback on two engines simultaneously, and two reports of power 
rollback on one engine. Ingestion of accreted ice, if not prevented, 
could result in multiple engine power rollback during flight in 
freezing precipitation conditions.
    Jetstream has issued Service Bulletin ATP-30-39-30146A 
(Modification 30146A), dated July 29, 1994, which describes procedures 
for installing modified de-ice timers for the left and right engines. 
The modified de-ice timers will provide additional electric power 
directly to the engine air intake flange heater. This additional 
electric load requires revision of electric load shedding procedures in 
the event of electrical system failure. These procedures are included 
in the Jetstream Aircraft ATP Airplane Flight Manual (AFM), Temporary 
Revision T/41, Issue 1, dated November 15, 1994.
    Jetstream has also issued Service Bulletin ATP-30-37-30143A 
(Modification 30143A), dated August 1, 1994, and Revision 1, dated 
September 5, 1994, which describe procedures for installation of 
modified electrical wiring for flexible ducts and lips of the engine 
air intake. This modification automates turning on the de-ice heaters 
in the flexible duct of the engine air intake when the lip heat is on. 
The modification continues to allow pilots to select the de-ice systems 
of the engine air intake manually, via the ``All On'' switch of the 
anti-ice system.
    The CAA classified these service bulletins as mandatory, in order 
to assure the continued airworthiness of these airplanes in the United 
Kingdom.
    Jetstream has also issued Service Bulletin ATP-30-30-35285A, dated 
July 15, 1994, which describes procedures for installation of a system 
that automates a 20-second delay between the time that the left engine 
intake de-ice systems are turned on and the time that the right engine 
intake de-ice systems are turned on. This modification also reduces 
pilot workload by automatically turning on the engine de-ice system at 
an interval 20 seconds apart for the left and right engines when the 
engine intake de-ice is selected to ``on.'' The automated 20-second 
time delay ensures that the de-ice system for the left and right engine 
intakes will be turned on in such a way as to prevent simultaneous 
rollbacks of the engines in icing conditions. The CAA has not 
classified this service bulletin as mandatory. However, the FAA has 
determined that the pilot could easily neglect to heed the necessary 
20-second delay if manually turning on the second flexible duct de-ice 
system; this could cause accumulated ice in the air intake ducts of 
both engines to dislodge simultaneously and be ingested into the 
engines, which then could result in rollback of both engines at the 
same time. In light of this, the FAA considers that the modification 
described in this service bulletin is necessary.
    This airplane model is manufactured in the United Kingdom and is 
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. Pursuant 
to this bilateral airworthiness agreement, the CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, reviewed all available information, and determined 
that AD action is necessary for products of this type design that are 
certificated for operation in the United States.
    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 installation of new 
de-ice timers and an associated revision to the AFM; installation of a 
system that automates a 20-second delay between turning on the left 
engine intake de-ice system and turning on the right engine intake de-
ice system; and installation of modified electrical wiring for the 
flexible ducts and lips of the engine air intake. These actions would 
be required to be accomplished in accordance with the service bulletins 
described previously.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this notice to clarify this requirement.
    The FAA estimates that 10 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 72 work 
hours per airplane to accomplish the proposed actions, and that the 
average labor rate is $60 per work hour. Required parts would be 
provided by the manufacturer at no cost to the operators. Based on 
these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $43,200, or $4,320 per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Jetstream Aircraft Limited (Formerly British Aerospace Commercial 
Aircraft, Limited) Docket 94-NM-158-AD

    Applicability: Model ATP airplanes; having constructor numbers 
2002 through 2063, inclusive; 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 use the authority 
provided in paragraph (c) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent engine power rollback during flight in icing 
conditions, due to ingestion of accreted ice, accomplish the 
following:
    (a) For airplanes having constructor numbers 2002 through 2056, 
inclusive: Within 90 days after the effective date of this AD, 
install modified de-ice timers for the left and right engines 
(Modification 30146A), in accordance with Jetstream Aircraft Limited 
Service Bulletin ATP-30-39-30146A, dated July 29, 1994; and revise 
the FAA-approved Airplane Flight Manual (AFM) to include the 
information specified in Temporary Revision T/41, Issue 1, dated 
November 15, 1994.

    Note 2: The revision of the AFM required by this paragraph may 
be accomplished by inserting a copy of Temporary Revision T/41 in 
the AFM. When this temporary revision has been incorporated into 
general revisions of the AFM, the general revisions may be inserted 
in the AFM, provided that the information contained in the general 
revision is identical to that specified in Temporary Revision T/41.

    (b) For airplanes having constructor numbers 2002 through 2063, 
inclusive: Within 90 days after the effective date of this AD, 
accomplish paragraphs (b)(1) and (b)(2) of this AD:
    (1) Install the modified electrical wiring for the flexible 
ducts and lips of the engine air intake (Modification 30143A) in 
accordance with Jetstream Aircraft Limited Service Bulletin ATP-30-
37-30143A, dated August 1, 1994, or Revision 1 dated September 5, 
1994.
    (2) Install the automated 20-second delay system (Modification 
35285A), to ensure that the left engine de-ice systems are turned on 
prior to turning on the right engine de-ice systems, in accordance 
with Jetstream Aircraft Limited Service Bulletin ATP-30-30-35285A, 
dated July 15, 1994; and revise the FAA-approved AFM to include the 
information specified in Temporary Revision T/40, Issue 1, dated 
August 3, 1994.

    Note 3: The revision of the AFM required by this paragraph may 
be accomplished by inserting a copy of Temporary Revision T/40 in 
the AFM. When this temporary revision has been incorporated into 
general revisions of the AFM, the general revisions may be inserted 
in the AFM, provided the information contained in the general 
revision is identical to that specified in Temporary Revision T/40.

    (c) 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, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Maintenance Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (d) 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 December 14, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-31182 Filed 12-19-94; 8:45 am]
BILLING CODE 4910-13-U