[Federal Register Volume 63, Number 1 (Friday, January 2, 1998)]
[Notices]
[Page 137]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-34159]



  Federal Register / Vol. 63, No. 1 / Friday, January 2, 1998 / 
Notices  

[[Page 137]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Proposed Advisory Circular (AC) 120-XX, Repair Assessment of 
Pressurized Fuselages

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed advisory circular.

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SUMMARY: This notice invites pubic comment on a proposed Advisory 
Circular (AC) which provides guidance as to acceptable means of 
accomplishing the requirements of a proposed rule on the subject of 
repair assessment of pressurized fuselages published elsewhere in the 
issue of the Federal Register 

DATES: Comments must be received on or before April 2, 1998.

ADDRESSES:  Send all comments on the proposed AC to: Dorenda Baker, 
Manager, Aging Aircraft Program, ANM-109, FAA Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Ave SW., Renton, 
WA 98055-4056. Comments may be examined at the above address between 
7:30 a.m. and 4:00 p.m. weekdays, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:
Pat Siegrist, Regulations Branch, ANM-114, FAA Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, WA 98055-4056; telephone (425) 227-2126.

SUPPLEMENTARY INFORMATION:

Comments Invited

    A copy of the subject AC may be obtained by contacting the person 
named above under FOR FURTHER INFORMATION CONTACT. Interested persons 
are invited to comment on the proposed AC by submitting such written 
data, views, or arguments as they may desire. Commenters must identify 
the title of the AC and submit comments in duplicate to the address 
specified above. All comments received on or before the closing date 
for comments will be considered by the Transport Airplane Directorate 
before issuing the final AC.

Discussion

    Advisory Circular (AC) 120-xx, Repair Assessment of Pressurized 
Fuselages, has been written to provide guidance on how to incorporate 
FAA-approved repair assessment guidelines into an operator's FAA-
approved maintenance or inspection program as proposed in [insert 
notice number], published elsewhere in this issue of the Federal 
Register. The draft AC provides proposed guidance as to acceptable 
means of accomplishing the requirements of the rule. The following is a 
summary of the contents of the AC:
    1. Repair Assessment Process. Assessment of existing repairs 
installed on the fuselage pressure boundary of affected airplanes will 
establish a damage-tolerance based structural inspection program and 
replacement times, where needed. Utilizing the repair assessment 
guidelines developed by the manufacturers of the affected airplanes, 
two principle techniques have been identified that can be used to 
accomplish the repair assessment.
    2. Implementation. The proposed rule would require the repair 
assessment guidelines to be approved by the Aircraft Certification 
Office having cognizance over the type certificate for the affected 
airplane. The means by which the repair assessment guidelines would be 
incorporated into the FAA-approved maintenance or inspection program 
would be subject to the approval of the certificate holder's principle 
maintenance inspector (PMI) or other cognizant airworthiness inspector.
    3. Recommended schedule for accomplishing the repair assessment. 
The repair assessment activity should be completed in accordance with 
the schedule in the FAA Approved Repair Assessment Guidelines for each 
of the affected airplanes. Any necessary corrective actions to be taken 
as a result of the evaluation would be incorporated into the FAA-
approved maintenance or inspection program.
    4. New Repairs. The operator would have to assess new repairs using 
the assessment guidelines, unless the new repairs are accomplished 
according to structural repair manuals, or any other equivalent method 
that incorporates damage tolerance methods of design and evaluation. 
The aircraft manufacturers of the affected models are updating their 
structural repair manuals to address damage tolerance methodology. FAA 
Advisory Circular 25.1529-1, ``Instructions for Continued Airworthiness 
of Structural Repairs on transport Airplanes,'' provides guidance for 
installing new damage tolerance based repairs.
    5. Sale and Transfer of Airplanes. Before an airplane is added to 
an operator's operations specifications, a program for accomplishment 
of the repair assessment should be established.
    6. Repairs to Structural Modification Certified by a Supplemental 
Type Certificate (STC). The operator would need to establish a repair 
assessment program for structure modified by an STC.

    Issued in Washington, D.C. on December 22, 1997.
Thomas E. McSweeny,
Director, Aircraft Certification Service.
[FR Doc. 97-34159 Filed 12-31-97; 8:45 am]
BILLING CODE 4910-13-M