[Federal Register Volume 59, Number 220 (Wednesday, November 16, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-28245]


[[Page Unknown]]

[Federal Register: November 16, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-126-AD]

 

Airworthiness Directives; British Aerospace Model BAe 146-100A, -
200A, and -300A 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 all British Aerospace Model BAe 
146-100A, -200A, and -300A series airplanes. This proposal would 
require conducting closed loop tests to determine the setting of the 
underfrequency trip level on suspect generator control units (GCU), and 
either the correction of discrepancies or replacement of the GCU. This 
proposal is prompted by several malfunctions of in-service GCU's due to 
the effects of setting the underfrequency trip level too high. The 
actions specified by the proposed AD are intended to correct GCU's that 
may have the underfrequency level set too high, which could result in 
the unwanted shut down of an electrical generator; this condition may 
lead to loss of all generated electrical power on the airplane when 
other generator faults or failures occur.

DATES: Comments must be received by January 13, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-126-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 British Aerospace Holdings, Inc., Avro International 
Aerospace Division, P.O. Box 16039, Dulles International Airport, 
Washington DC 20041-6039; and GEC-Marconi Aerospace Ltd, Titchfield, 
Fareham, Hampshire P014 4QA, England. 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, 
ANM-113, 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-126-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-126-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 all British Aerospace Model BAe 146-100A, 
-200A, and -300A series airplanes. The CAA advises that reports have 
been received of several malfunctions of in-service generator control 
units (GCU). Investigation revealed that GCU's repaired or adjusted by 
workshops other than GEC-Marconi may have the underfrequency trip level 
set too high. The cause has been attributed to the fact that the GEC-
Marconi Component Maintenance Manual does not recommend that the 
underfrequency trip level be checked during the closed loop test. (GEC-
Marconi is the manufacturer of the subject GCU's.) Setting the 
underfrequency level too high could lead to the shut down of an 
electrical generator. If an electrical generator shuts down when other 
generator faults or failures occur, all generated electrical power on 
the airplane may be lost.
    Avro International Aerospace (a division of British Aerospace) has 
issued Service Bulletin S.B. 24-103, dated March 24, 1994, which 
describes procedures for checking the part and serial number on the 
data plate of each GCU to identify discrepant units, replacing the 
discrepant GCU with a serviceable unit, and conducting post assembly 
testing. The CAA classified this service bulletin as mandatory.
    GEC-Marconi has issued Service Bulletin HGE 24-23, dated March 11, 
1994, which describes procedures for conducting closed loop tests to 
determine the setting of the underfrequency trip level, adjusting the 
underfrequency trip level, and conducting post assembly testing. This 
service bulletin also describes the part and serial number of affected 
GCU's.
    This airplane model is manufactured in the United Kingdom and is 
type certificated for operation in the United States under the 
provisions of Sec. 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 checking the part 
and serial number on the data plate of each GCU to identify discrepant 
units, and conducting closed loop tests on affected GCU's to determine 
the setting of the underfrequency trip level. The proposed AD would 
also require either adjusting the underfrequency trip level or 
replacing the discrepant GCU with a serviceable unit, and conducting 
post assembly testing. The actions would be required to be accomplished 
in accordance with the service bulletins described previously.
    The FAA estimates that 43 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 actions, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be $2,580, or $60 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:

British Aerospace Regional Aircraft Limited, AVRO International 
Aerospace Division (Formerly British Aerospace, plc; British 
Aerospace Commercial Aircraft Limited): Docket 94-NM-126-AD.

    Applicability: All Model British Aerospace Model BAe 146-100A, -
200A, and -300A series airplanes, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously. -To correct generator control units (GCU) that may have 
the under-frequency trip level set too high, which could lead to the 
unwanted shut down of an electrical generator, accomplish the 
following:
    (a) Within 6 months after the effective date of this AD, check 
the part and serial number on the data plate of each generator 
control unit (GCU). If the part number is one of those affected and 
the serial number is listed in Addendum 1 of GEC-Marconi Service 
Bulletin HGE 24-23, dated March 11, 1994, prior to further flight, 
conduct a closed loop test to determine the setting of the 
underfrequency trip level, in accordance with that service bulletin.
    (1) If the level exceeds that specified in GEC-Marconi Service 
Bulletin HGE 24-23, dated March 11, 1994, prior to further flight, 
adjust the level in accordance with that service bulletin; or 
replace the GCU with a serviceable unit, in accordance with Avro 
Service Bulletin S.B. 24-103, dated March 24, 1994.
    (2) Prior to further flight, after adjustment or replacement of 
the GCU as required by paragraph (a)(1) of this AD, conduct the post 
assembly testing in accordance with Avro Service Bulletin S.B. 24-
103, dated March 24, 1994.
    (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, 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: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (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.

    Issued in Renton, Washington, on November 9, 1994.
S.R. Miller, Acting Manager,
Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 94-28245 Filed 11-15-94; 8:45 am]
BILLING CODE 4910-13-U