[Federal Register Volume 59, Number 31 (Tuesday, February 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3460]
[[Page Unknown]]
[Federal Register: February 15, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-NM-228-AD]
Airworthiness Directives; Boeing Model 767 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 Boeing Model 767 series
airplanes. This proposal would require dye penetrant inspection and
proof pressure testing to detect cracks or ruptures of the crossover
pneumatic duct, and repair or replacement, as necessary. This proposal
would also require stress relieving of the crossover pneumatic duct
assembly. This proposal is prompted by several reports of ruptured
engine bleed air crossover ducts. The actions specified by the proposed
AD are intended to prevent failure of the engine bleed air crossover
duct, which could result in loss of pneumatics and damage to adjacent
structure.
DATES: Comments must be received by April 11, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 93-NM-228-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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Barbara Mudrovich, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S; Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone
(206) 227-2670; fax (206) 227-1181.
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 93-NM-228-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. 93-NM-228-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On July 14, 1993, the FAA issued AD 93-14-11, Amendment 39-8635 (58
FR 43550, August 17, 1993), applicable to Boeing Model 767 series
airplanes, line position 001 through 307, inclusive. That AD requires a
dye penetrant inspection and proof pressure testing to detect cracks or
ruptures of the crossover pneumatic ducts, and repair or replacement,
as necessary. That action was prompted by several reported incidents of
ruptured engine bleed air crossover ducts on certain Boeing Model 767
series airplanes. The duct ruptures resulted in a loss of cabin
pressure, loss of bleed air to the air driven hydraulic pump, loss of
wing thermal anti-ice capabilities, and damage to the air conditioning
panels. These duct ruptures were caused by cracking, which started and
progressed around the circumferential welds. These cracks formed in the
heat affected zones of the duct welds because of hydrogen oxide
(hydride) concentration. The hydrides have an embrittling effect on the
duct material, which may initiate the cracking.
Duct ruptures, if not corrected, could result in loss of pneumatics
for cabin pressurization, air conditioning, air driven hydraulic pump,
wing thermal anti-ice, hydraulic reservoir pressurization, engine cross
starting ability, and cargo heating, and could also damage air
conditioning panels.
Since the issuance of AD 93-14-11, the manufacturer has discovered
that stress relieving of one of the four crossover ducts was
incorporated during production on airplanes starting at line number 322
instead of line number 308. The manufacturer has informed the FAA that
14 airplanes did not receive stress relieving of the crossover duct.
Therefore, these 14 airplanes would be subject to the same unsafe
condition as addressed by AD 93-14-11.
The FAA has reviewed and approved Boeing Service Bulletin 767-
36A0041, Revision 2, dated October 28, 1993, that describes procedures
for conducting dye penetrant inspections and proof pressure tests of
the crossover pneumatic duct. This service bulletin also describes
procedures for repairing or replacing this duct, and stress relieving
this duct. Stress relieving this duct will eliminate the residual
stress and local stress concentration. A dye penetrant inspection,
proof pressure test, and stress relieving will reduce the possibility
of engine bleed air crossover duct rupture caused by cracking due to
hydride formation. The effectivity listing of this service bulletin
includes the 14 airplanes on which the stress relieving procedure was
not accomplished during production.
Since an unsafe condition has been identified that is likely to
exist on other products of this same type design, the proposed AD would
require conducting dye penetrant inspections and proof pressure tests
of the crossover pneumatic duct on 14 specific airplanes. This proposed
AD would also require repairing or replacing this duct, and stress
relieving this duct. The actions would be required to be accomplished
in accordance with the service bulletin described previously.
(Note: The FAA's normal policy is that, when an AD requires a
substantive change, such as a change in its applicability, the
``old'' AD is superseded by being removed from the system and a new
AD added. In the case of this AD action, the FAA normally would have
proposed superseding AD 93-14-11 to expand its applicability to
include the 14 additional airplanes. However, in reconsideration of
the entire fleet size that would be affected by such a supersedure
action, and the consequent workload associated with revising
maintenance record entries, the FAA has determined that a less
burdensome approach is to issue a separate AD applicable only to the
14 airplanes. This AD does not supersede AD 93-14-11; airplanes
listed in the applicability of AD 93-14-11 continue to be required
to comply with the requirements of that AD. This proposed AD is a
separate AD action, and is applicable only to airplanes having line
numbers 308 through 321, inclusive.)
There are 14 Model 767 series airplanes of the affected design in
the worldwide fleet. The FAA estimates that 6 airplanes of U.S.
registry would be affected by this proposed AD, that it would take
approximately 18 work hours per airplane to accomplish the proposed
actions, and that the average labor rate is $55 per work hour. Required
parts would cost approximately $2,208 per airplane. Based on these
figures, the total cost impact of the proposed AD on U.S. operators is
estimated to be $19,188, or $3,198 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:
Boeing: Docket 93-NM-228-AD.
-Applicability: Model 767 series airplanes, line position 308
through 321 inclusive, certificated in any category. -
Compliance: Required as indicated, unless accomplished
previously.
-Note 1: Inspections, testing, and repair or replacement
accomplished prior to the effective date of this amendment in
accordance with Boeing Alert Service Bulletin 767-36A0041, dated
July 2, 1992; or Revision 1, dated February 25, 1993; are considered
acceptable for compliance with the applicable action specified in
this amendment. -
To prevent failure of the engine bleed air crossover duct, which
could result in loss of pneumatics and damage to adjacent structure,
accomplish the following: -
(a) OPTION 1: As an alternative to the requirements of paragraph
(b) of this AD, accomplish the following: -
(1) Within 6 months after the effective date of this AD, or
prior to the accumulation of 7,000 total flight cycles, whichever
occurs later, conduct a dye penetrant inspection and proof pressure
test of the crossover pneumatic duct, in accordance with Boeing
Service Bulletin 767-36A0041, Revision 2, dated October 28, 1993. -
(i) If cracks or ruptures are detected, prior to further flight,
repair or replace the crossover pneumatic duct in accordance with
the service bulletin. -
(ii) Stress relieving of the duct, in accordance with the
service bulletin, may be accomplished in conjunction with the
initial dye penetrant inspection and proof pressure test required by
this paragraph. Such action constitutes terminating action for the
requirements of paragraph (a)(2) of this AD. -
(2) Within 3,000 flight cycles after accomplishing the initial
dye penetrant inspection and proof pressure test required by
paragraph (a)(1) of this AD, conduct an additional dye penetrant
inspection and proof pressure test of the crossover pneumatic duct,
and stress relieve the crossover pneumatic duct assembly, in
accordance with Boeing Service Bulletin 767-36A0041, Revision 2,
dated October 28, 1993. If cracks or ruptures are detected, prior to
further flight, repair or replace the crossover pneumatic duct in
accordance with the service bulletin. -
(b) OPTION 2: As an alternative to the requirements of paragraph
(a) of this AD, accomplish the following: -
(1) Within 18 months after the effective date of this AD, or
prior to the accumulation of 7,000 total flight cycles, whichever
occurs later, conduct a dye penetrant inspection and proof pressure
test of the crossover pneumatic duct and stress relieve the
crossover pneumatic duct assembly, in accordance with Boeing Service
Bulletin 767-36A0041, Revision 2, dated October 28, 1993. -
(2) If cracks or ruptures are detected, prior to further flight,
repair or replace the crossover pneumatic duct in accordance with
the service bulletin. -
(c) Replacement of the crossover pneumatic duct with a stress
relieved duct in accordance with Boeing Service Bulletin 767-
36A0041, Revision 2, dated October 28, 1993, constitutes terminating
action for the requirements of paragraphs (a) and (b) of this AD.
(d) 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, Seattle Aircraft Certification
Office (ACO), 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, Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
-(e) 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 9, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-3460 Filed 2-14-94; 8:45 am]
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