AD 2001-08-10

This AD becomes effective on June 12, 2001.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulations as of June 12, 2001.

You may get the service information referenced in this AD from Aerostar Aircraft Corporation, 10555 Airport Drive, Hayden Lake, ID 83835; telephone: (208) 762-0338; facsimile: (208) 762-8349. You may read this information at the Federal Aviation Administration (FAA), Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2000-CE-31-AD, 901 Locust, Room 506, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Richard Simonson, Aerospace Engineer, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW, Renton, Washington 98055; telephone: (425) 227-2597; facsimile: (425) 227-1181.

The FAA has received several reports of cracking of the main landing gear lower side brace at the upper bolt lug discovered on preflight inspection of Aerostar PA-60 Model airplanes. Damage or cracking of the main landing gear lower side brace, if not detected and corrected, could result in failure of this part. Such failure could lead to loss of the main landing gear with consequent loss of control of the airplane.

Aerostar has issued Service Bulletin SB600-134A, dated March 31, 2000. The service bulletin includes procedures for replacing both existing main landing gear lower side brace assemblies with parts of improved design, Aerostar part number 400084-001, lower side brace assemblies.

Has FAA taken any action to this point? We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Aerostar Models PA-60-600, PA-60-601, PA-60-601P, PA-60-602P, and PA-60-700P airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on November 24, 2000 (65 FR 70535). The NPRM proposed to require you to replace both of the existing main landing gear lower side brace assemblies with parts of improved design

What is the potential impact if FAA took no action? Damage or cracks in the main landing gear lower side brace at the upper bolt lug where the upper and lower side braces connect could result in failure of the main landing gear lower side brace. Such failure could lead to loss of control of the airplane.

Was the public invited to comment? The FAA encouraged interested persons to participate in the making of this amendment. The following presents the comments received on the proposal and FAA's response to these comments:

What is the commenter's concern? Ten commenters state that their inspections have not shown any evidence of the problem described in the NPRM. They note that requiring replacement of these side braces with new parts imposes an undue financial burden on the airplane owners. Lastly, the commenters write that the repetitive inspections provide a sufficient level of safety for this airplane.

What is FAA's response to the concern? The FAA disagrees. There have been four reported cases, so far, of cracking in the upper bolt lug of this brace. More sophisticated analysis techniques than those available at the time of the initial airplane design show that the original braces do not meet the requirements of the Federal Aviation Regulations (14 CFR). As a result, the part was redesigned.

Fatigue cracks are extremely hard to detect early to avoid failure of the main landing gear lower side brace. The failure of a brace is hazardous. At the very least, the failure will result in severe damage to the airplane, with the possibility of follow-on damage to the airplane, and death or injury to the flight crew, passengers, and bystanders. For the above reasons, the original side braces must be replaced.

We are not changing the AD based on these comments.

What is FAA's Final Determination on this Issue? We carefully reviewed all available information related to the subject presented above and determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. We determined that these minor corrections:

—Will not change the meaning of the AD; and

—Will not add any additional burden on the public than was already proposed.

How many airplanes does this AD impact? We estimate that this AD affects 650 airplanes in the U.S. registry.

What is the cost impact of this AD on owners/operators of the affected airplanes? We estimate the following costs to accomplish the modification:

Does this AD impact various entities? The regulations adopted 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. We have determined that this rule would not have federalism implications under Executive Order 13132.

Does this AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this action (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. A copy of the final evaluation prepared for this action is contained in the Rules Docket. You may get a copy of it from the Rules Docket at the location provided under the caption ADDRESSES.

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

1. The authority citation for part 39 continues to read as follows:

2. FAA amends § 39.13 by adding a new AD to read as follows: