[Federal Register Volume 59, Number 34 (Friday, February 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3755]


[[Page Unknown]]

[Federal Register: February 18, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-217-AD]

 

Airworthiness Directives; British Aerospace 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 British Aerospace Model 
ATP airplanes. This proposal would require inspections of the DC 
connections and cooling fans in certain transformer rectifier units 
(TRU) to detect damage or overheating and to ensure correct operation, 
and repair or replacement, if necessary. This proposal is prompted by a 
report of the loss of all DC electrical power, except for the battery 
emergency bus, due to failure of the TRU's, which occurred during 
flight. The actions specified by the proposed AD are intended to 
prevent loss of essential electrical power required to continue safe 
flight of the airplane.

DATES: Comments must be received by April 18, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 93-NM-217-AD, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 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 No. 93-NM-217-AD.'' The postcard will be 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. 93-NM-217-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 British Aerospace Model ATP 
airplanes. The CAA advises that it has received a report of the loss of 
all DC electrical power, except for the battery emergency bus, which 
occurred during flight on a Model ATP airplane. The DC electrical power 
was lost due to a failure in each of the two transformer rectifier 
units (TRU's.) A loose DC connection in the first TRU caused its 
failure. The second TRU failed due to overheat damage to a cooling fan 
blade in the unit. The airplane landed safely while operating on 
battery power. Failure of both TRU's during flight could result in loss 
of essential electrical power required to continue safe flight of the 
airplane.
    Jetstream has issued Service Bulletin ATP-24-58, dated October 29, 
1993, which references two Ferranti service bulletins as additional 
sources of service information. (Ferranti is the manufacture of the 
TRU's). The Ferranti service bulletins are described below. The CAA 
classified the Jetstream service bulletin as mandatory.
    Ferranti Service Bulletin 24-20-171, dated September 1993, 
describes procedures for repetitive visual inspections of the DC 
connections to detect any damage or overheating. This service bulletin 
also describes procedures for repetitive torque loading inspections of 
each DC connection to ensure that torque loads are within specified 
limits, and repetitive verification that each terminal stud is secure 
in its mounting by visually observing that the stud does not rotate.
    Ferranti Service Bulletin 24-20-172, dated September 1993, 
describes procedures for repetitive visual inspections of the cooling 
fan blades to detect any damage due to overheating, and a test of the 
operation of the cooling fan by energizing the relay and confirming 
that cooling air exists from the grill on the top of the unit.
    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 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:
    1. Repetitive visual inspections of the DC connections to detect 
any damage or overheating, and repair, if necessary;
    2. Repetitive torque loading inspections of each DC connection to 
ensure that torque loads are within specified limits, and verification 
that each terminal stud is secure in its mounting;
    3. Repetitive visual inspections of the cooling fan blades to 
detect any damage due to overheating, and replacement of the fan blade, 
if necessary; and
    4. Repetitive functional tests of the operation of the cooling fan 
by energizing the relay and confirming that cooling air exits from the 
grill on the top of the unit, and repair or replacement of any 
malfunctioning or damaged cooling fan or cooling fan relay.
    The inspection would be required to be accomplished in accordance 
with the Ferranti service bulletins described previously. Replacement 
and repair actions would be required to be accomplished in accordance 
with the airplane maintenance manual or a method approved by the FAA.
    The FAA estimates that 10 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 2 work 
hours per airplane to accomplish the proposed actions, and that the 
average labor rate is $55 per work hour. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be $1,100, or $110 per airplane. This total cost figure assumes that no 
operator has yet accomplished the proposed requirements of this AD 
action.
    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 14 
CFR part 39 of the Federal Aviation Regulations 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 (Commercial Aircraft), Limited: Docket 93-NM-217-
AD.

    Applicability: Model ATP airplanes equipped with Ferranti 
Transformer Rectifier Unit TR202A (Pt. No. 84/59100) or TR202B (Pt. 
No. 84/60040), certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loss of essential electrical power required to 
continue safe flight of the airplane, accomplish the following:
    (a) Within 225 hours time-in-service after the effective date of 
this AD, and thereafter at intervals not to exceed 625 hours time-
in-service, accomplish paragraphs (a)(1), (a)(2), (a)(3), and (a)(4) 
of this AD.
    (1) Perform a visual inspection of the DC connections to detect 
any damage or overheating, in accordance with Ferranti Service 
Bulletin 24-20-171, dated September 1993. If any damage or 
overheating is found, prior to further flight, repair in accordance 
with a method approved by Manager, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate.
    (2) Perform a torque loading inspection of each DC connection to 
ensure that torque loads are within the limits specified in Ferranti 
Service Bulletin 24-20-171, dated September 1993; and, during this 
inspection, ensure that each terminal stud is secure in its mounting 
by visually observing that the stud does not rotate; in accordance 
with Ferranti Service Bulletin 24-20-171, dated September 1993.
    (3) Perform a visual inspection of the cooling fan blades to 
detect any damage due to overheating, in accordance with Ferranti 
Service Bulletin 24-20-172, dated September 1993. If any damage is 
found, prior to further flight, replace the fan blade with a 
serviceable part in accordance with the airplane maintenance manual.
    (4) Perform a functional test of the operation of the cooling 
fan by energizing the relay and confirming that cooling air exits 
from the grill on top of the unit, in accordance with Ferranti 
Service Bulletin 24-20-172, dated September 1993. Prior to further 
flight, repair or replace any malfunctioning or damaged cooling fan 
or cooling fan relay, in accordance with the airplane maintenance 
manual.
    (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 FAR 
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 February 14, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-3755 Filed 2-17-94; 8:45 am]
BILLING CODE 4910-13-M