AD 91-15-24

AD Final Rules - DRS_91-15-24.html
Copy URL
Print/Save as PDF
Document Versions
 Feedback
Details
AD Number:
91-15-24
Document Type:
AD Final Rules
Docket Number:
91-NM-14-AD
Subject Heading:
Airworthiness Directives; BOEING Model 747 Series Airplanes
Subject:
Auxiliary Power Unit Pneumatic Ducts Inspection
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
09/09/1991
Make:
The Boeing Company
Model:
747-100 Series | 747-100B Series | 747-100B SUD Series | 747-200B Series | 747-200C Series | 747-200...Show more
Product Type:
Aircraft
Product Subtype:
Large Airplane
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 91-15-24
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   91-NM-14-AD

AMENDMENT:   39-7089

AD NUMBER:   91-15-24

SUBJECT HEADING:   Airworthiness Directives; BOEING Model 747 Series Airplanes

ACTION:  

SUMMARY:  

DATES:   Effective September 9, 1991.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
91-15-24 BOEING: Amendment 39-7089. Docket No. 91-NM-14-AD.

Applicability: Model 747 series airplanes, line positions 2 through 720 for Auxiliary Power Unit (APU) pneumatic ducts in body sections 44, 46, and 48; and line positions 721 through 734 for APU pneumatic ducts in body sections 44 and 48; certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent damage to adjacent structure, pneumatic ducts, hydraulic lines, and/or electrical wiring as a result of failure of Auxiliary Power Unit (APU) pneumatic ducts, accomplish the following:

A. Prior to the accumulation of 7,000 flight cycles, or within the next 3,000 flight cycles after the effective date of this AD, whichever occurs later, conduct a penetrant inspection, proof pressure test, and penetrant inspection again to detect cracks or ruptures in the APU pneumatic ducts in accordance with the Accomplishment Instructions, Items A. through G., K., O., and P. of Boeing Service Bulletin 747-36-2081, dated November 29, 1990. If cracks or ruptures are detected, prior to further flight, repair or replace in accordance with the service bulletin. The stress relieving procedure specified in Accomplishment Instructions, Items H., I., and J. of the service bulletin may be accomplished in conjunction with the penetrant inspection and proof pressure test required by this paragraph, and constitutes terminating action for the requirements of paragraph B. of this AD for all APU pneumatic ducts.

B. Prior to the accumulation of 7,000 flight cycles after the accomplishment of the initial inspection required by paragraph A. of this AD, conduct an additional penetrant inspection, proof pressure test, and penetrant inspection of the APU pneumatic ducts, and stress relieve the APU pneumatic duct assemblies, in accordance with the Accomplishment Instructions, Items A. through K., O., and P. of Boeing Service Bulletin 747-36-2081, dated November 29, 1990. If cracks or ruptures are detected, prior to further flight, repair or replace in accordance with the service bulletin.

C. Replacement of all APU pneumatic ducts in accordance with Accomplishment Instructions A., B., L. through O., and P. of Boeing Service Bulletin 747-36-2081, dated November 29, 1990; or in accordance with Boeing Service Bulletin 747-36-2092, dated June 28, 1990; constitutes terminating action for the requirements of this AD.

D. An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO.

E. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

F. The penetrant inspections, proof pressure testing, and stress relieving shall be done in accordance with Boeing Service Bulletin 747-36-2081, dated November 29, 1990. APU pneumatic duct replacement shall be done in accordance with either Boeing Service Bulletin 747- 36-2081, dated November 29, 1990, or Boeing Service Bulletin 747-36-2092, dated June 28, 1990. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington, or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C.

This amendment (39-7089, AD 91-15-24) becomes effective on September 9, 1991.

FOOTER: