[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]


-----------------------------------------------------------------------


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).

-----------------------------------------------------------------------

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]
BILLING CODE 4910-13-U