[Federal Register Volume 62, Number 89 (Thursday, May 8, 1997)]
[Proposed Rules]
[Pages 25151-25152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-12040]



[[Page 25151]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-229-AD]
RIN 2120-AA64


Airworthiness Directives; Saab Model SAAB 2000 Series 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 Saab Model SAAB 2000 
series airplanes. This proposal would require replacement of the 
ignition exciter in the auxiliary power unit with a part that is 
designed to operate better in cold weather. This proposal is prompted 
by two occurrences of the auxiliary power unit (APU) failing to start 
after flight in cold soak conditions. The actions specified by the 
proposed AD are intended to prevent such APU failure, which could 
result in the inability of the APU to restart the engines in the event 
both engines quit operating during flight.

DATES: Comments must be received by June 19, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-229-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 SAAB Aircraft AB, SAAB Aircraft Product Support, S-
581.88, Linkoping, Sweden. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Ruth Harder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1721; fax (206) 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 96-NM-229-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. 96-NM-229-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Luftfartsverket (LFV), which is the airworthiness authority for 
Sweden, recently notified the FAA that an unsafe condition may exist on 
certain Saab Model SAAB 2000 series airplanes. The LFV advises that the 
auxiliary power unit (APU), part number 4500090 (serial numbers SP-
E941224, and SP-E941228 through SP-E951259 inclusive), could fail to 
start in temperatures below -4 degrees F (-20 degrees C) after flight 
of two hours or more in cold soak conditions. At these temperatures, 
the electrical current to the ignition exciter in the auxiliary power 
unit is too high. This causes the over-current protection circuit in 
the Electronic Sequence Unit (ESU) to release, thus causing failure of 
the APU to start (ESU BITE-EXTERNAL SHORT). This condition, if not 
corrected in a timely manner, could result in the inability of the APU 
to restart the engines in the event both engines quit operating during 
flight.

Explanation of Relevant Service Information

    Saab has issued Service Bulletin 2000-49-005, dated December 19, 
1995, which describes procedures for replacing the ignition exciter, 
part number 4950787, with an ignition exciter having part number 
179420-2, which is designed to operate better in cold weather. The LFV 
classified this service bulletin as mandatory and issued Swedish 
airworthiness directive (SAD) No 1-082, dated December 20, 1995, in 
order to assure the continued airworthiness of these airplanes in 
Sweden.

FAA's Conclusions

    This airplane model is manufactured in Sweden 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 LFV has kept the FAA informed of 
the situation described above. The FAA has examined the findings of the 
LFV, 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.

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 replacement of the 
ignition exciter in the auxiliary power unit with a part that is 
designed to operate better in cold weather. The proposed action would 
be required to be accomplished in accordance with the service bulletin 
described previously.

Cost Impact

    The FAA estimates that 3 Saab Model SAAB 2000 series airplanes of 
U.S. registry would be affected by this proposed AD, that it would take 
approximately 1 work hour per airplane to accomplish the proposed 
replacement, and that the average labor rate is $60 per work hour. 
Required parts would be provided by the manufacturer at no cost to 
operators. Based on these figures, the cost impact of the proposed AD 
on U.S. operators is estimated to be $180, or $60 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished the modification proposed by this AD

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action, and that no operator would accomplish this modification in the 
future if this AD were not adopted.

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:

SAAB Aircraft AB: Docket 96-NM-229-AD.

    Applicability: Model SAAB 2000 series airplanes, equipped with 
an auxiliary power unit (APU) having part number 4500090, serial 
numbers SP-E941224, and SP-E941228 through SP-E951259 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 
otherwise 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 (c) 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 auxiliary power unit (APU) failure, which could 
result in the inability of the APU to restart the engines in the 
event both engines quit operating during flight, accomplish the 
following:
    (a) Within 60 days after the effective date of this AD: Replace 
the ignition exciter, part number 4950787, with an ignition exciter 
having part number 179420-2, in accordance with Saab Service 
Bulletin 2000-49-005, dated December 19, 1995.
    (b) As of the effective date of this AD, no person shall install 
an ignition exciter having part number 4950787 on any airplane.
    (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 2: 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 May 2, 1997.
Neil D. Schalekamp,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-12040 Filed 5-7-97; 8:45 am]
BILLING CODE 4910-13-U