[Federal Register Volume 72, Number 38 (Tuesday, February 27, 2007)]
[Notices]
[Pages 8834-8835]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-3329]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Proposed Advisory Circular 120-XX, Damage Tolerance Inspections 
for Repairs and Alterations

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of Availability of Proposed Advisory Circular (AC) 120-
XX, and Request for Comments

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SUMMARY: This notice announces the availability of and requests 
comments on a proposed advisory circular (AC) which provides guidance 
to type certificate holders and supplemental type certificate holders 
for developing damage tolerance data that will support operator 
compliance with certain airworthiness standards. This proposed AC 
complements revisions to the airworthiness standards that are being 
proposed by a separate notice. This notice is necessary to give all 
interested persons an opportunity to present their views on the 
proposed AC.

DATES: We must receive your comments by April 20, 2007.

ADDRESSES: You must mail two copies of your comments on the proposed AC 
to: Federal Aviation Administration, Attention: Greg Schneider, 
Airframe and Cabin Safety Branch, ANM-115, FAA, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, WA 98057-3356. You can inspect comments at the above address 
between 7:30 a.m. and 4 p.m. weekdays, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Kenna Sinclair, Transport Standards 
Staff, at the address above, telephone (425) 227-1556.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite interested people to comment on the proposed AC by 
sending written data, views, or arguments. You should identify AC 120-
XX and send two copies of your comments to the address specified above. 
We will consider all communications received by the closing date for 
comments. We will consider comments received late if it is possible to 
do so without incurring expense or delay. The proposed AC can be found 
and downloaded from the Internet at http://www.faa.gov/aircraft/draft_docs. A paper copy of the proposed AC may be obtained by contacting the 
person named above under the caption FOR FURTHER INFORMATION CONTACT.

Discussion

    This proposed AC provides guidance material to support Type 
Certificate (TC) and Supplemental Type Certificate (STC) Holder 
compliance with proposed rulemaking title 14 Code of Federal 
Regulations (14 CFR) 25.1823, Supplemental Structural Inspections, 
Holders of type certificates--Repairs; 14 CFR 25.1825, Supplemental 
Structural Inspections, Holders of type certificates--Alterations and 
repairs to alterations; 14 CFR 25.1827, Supplemental Structural 
Inspections, Holders of and applicants for a Supplemental type 
certificate--Alterations and repairs to alterations. These proposed 
regulations would require TC Holders and STC Holders to develop damage 
tolerance data that would support operator compliance with 14 CFR 
121.1109 and 14 CFR 129.109, the Aging Airplane Safety Final Rule 
(AASFR) (currently found at Sec. Sec.  121.370(a) and 129.16) with 
respect to repairs and alterations. Sections 121.370(a) and 129.16 
require operators of certain transport airplane models to incorporate 
into their maintenance program damage tolerance-based inspections and 
procedures for structure susceptible to fatigue cracking that could 
contribute to a catastrophic failure. The proposed AC refers to that 
type of structure as fatigue critical structure. The proposed AC is 
applicable to repairs and alterations that affect fatigue critical 
structure.
    The proposed AC also provides guidance for new and existing repairs 
and alterations made to the original, as delivered, airplane structural 
configuration, as well as repairs to alterations. For compliance with 
Sec.  121.1109 and Sec.  129.109, operators will need to demonstrate 
that new and existing repairs and alterations will have an evaluation 
and damage

[[Page 8835]]

tolerance-based inspections or other procedures implemented, if needed.
    Following the guidance in this proposed AC is one means, but not 
the only means, of complying with the part 25 revisions proposed in 
Notice No. 05-11 entitled Damage Tolerance Data for Repairs and 
Alterations, which was published in the Federal Register on April 21, 
2006 (71 FR 20574). Issuance of AC 120-XX is contingent on final 
adoption of the proposed revisions to part 25.

    Issued in Washington, DC, on February 20, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

Dave Cann,
Manager, Aircraft Maintenance Division, Flight Standards Service.
[FR Doc. E7-3329 Filed 2-26-07; 8:45 am]
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