Discussion
We have received a report indicating that several upper engine mount bolts broke during installation. These bolts have part number (P/ N) NAS 636 and have "AFC'' or "A'' (AirFasco of Canton, Ohio) stamped on the bolt head. Upper engine mount bolts are used to attach the quick engine change (QEC) to the truss mounts in a four-bolt pattern (two upper and two lower bolts). The failures occurred on military versions of Lockheed Model 382, 382B, 382E, 382F, 382G, and 382J series airplanes. The discrepant bolts were located in the upper two positions of the four bolt pattern (different bolts are installed in the lower two positions and are not interchangeable with the bolts in the upper two positions). Investigation revealed that Lockheed has not approved AirFasco as a supplier of these bolts. Material hardness testing also revealed that the discrepant bolts do not meet hardness requirements. The cause for the inadequate hardness is improper heat treatment.
Failure of the upper engine mount bolts could result in reduced structural capability of an engine mount, and possible separation of a strut and engine from the airplane during flight.
The upper engine mount bolts are commercially available. We do not know whether any of the discrepant bolts were sold to commercial operators by the supplier or an agent. Therefore, the discrepant bolts might be installed on Lockheed Model 382, 382B, 382E, 382F, 382G, and 382J series airplanes.
FAA's Determination and Requirements of This AD
We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the(se) same type design(s). This AD requires, among other actions, an inspection to determine whether a certain upper engine mount bolt is installed, and replacement of any discrepant upper engine mount bolt with a new one.
FAA's Justification and Determination of the Effective Date
It is not known when or if the discrepant upper engine mount bolts might have been installed on affected airplanes. The QEC-to-truss mount joint is designed to be failsafe for a single failed upper engine mount bolt. If both bolts in the upper position of an upper engine mount are discrepant, the ability for this joint to carry the QEC loads is compromised, and consequently one upper engine mount bolt could fail. If one bolt in the upper position of an upper engine mount fails, the other bolt in the upper position of the upper engine mount could also fail within a short amount of time. Failure to replace these discrepant bolts greatly increases the risk of operating with a QEC attachment system that might be incapable of handling design level loads. Because of our requirement to promote safe flight of civil aircraft and the critical need to ensure the structural capability of an engine mount and the short compliance time involved with this action, this AD must be issued immediately.
Because an unsafe condition exists that requires the immediate adoption of this AD, we find that notice and opportunity for prior public comment hereon are impracticable and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments before it becomes effective. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include "Docket No. FAA-2008-0740; Directorate Identifier 2008-NM-077-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this AD because of those comments.
We will post all comments we receive, without change, to http:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this AD.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. "Subtitle VII: Aviation Programs,'' describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in "Subtitle VII, Part A, Subpart III, Section 44701: General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect 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.
For the reasons discussed above, I certify that this AD:
(1) Is not a "significant regulatory action'' under Executive Order 12866,
(2) Is not a "significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), and
(3) 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.
You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new AD: