[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
