AD 95-23-11 ACTIVE

This amendment adopts a new airworthiness directive (AD) that applies to certain Aerostar Aircraft Corporation (Aerostar) PA-60-600 series airplanes. This action requires repetitively inspecting the fuselage horizontal stabilizer attach fittings for cracks, and replacing any cracked fuselage horizontal stabilizer attach fitting. A report of several cracks found on the forward horizontal stabilizer attach spar fitting on an Aerostar Model PA-60-601P airplane prompted this action. The actions specified by this AD are intended to prevent undetected cracked fuselage horizontal attach fittings, which could result in the fuselage horizontal stabilizer separating from the airplane while in flight with subsequent loss of control of the airplane.

Final rule; request for comments.

95-23-11 AEROSTAR AIRCRAFT CORPORATION: Amendment 39-9431; Docket No. 95-CE-81-AD.

Applicability: The following model and serial number airplanes, certificated in any category:

Models
Serial Numbers
PA-60-600 Aerostar 600
60-0001-003 through 60-0933-8161262
PA-60-601 Aerostar 601
61-0001-004 through 61-0880-8162157
PA-60-601P Aerostar 601P
61P-0157-001 through 61P-0860-8163455
PA-60-602P Aerostar 602P
62P-0750-8165001 through 60-8365021

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect ofthe modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required initially within the next 25 hours time-in-service (TIS) after the effective date of this AD or within the next 2 calendar months after the effective date of this AD, whichever occurs first, unless already accomplished, and thereafter at intervals not to exceed 100 hours TIS or 12 calendar months, whichever occurs first.

To prevent the fuselage horizontal stabilizer from separating from the airplane while in flight because of cracked attach fittings, which, if not detected and replaced, could result in loss of control of the airplane, accomplish the following:

(a) Inspect the upper and lower horizontal flanges on the left and right sides of the following parts for cracks in accordance with the INSTRUCTIONS section of Aerostar Service Bulletin SB600-130, dated September 26, 1995.

(1) The part number (P/N) 210006-001 fitting (forward fuselage horizontal stabilizer attach fitting); and

(2) The P/N 210007-001 fitting (aft fuselage horizontal stabilizer attach fitting).

(b) Prior to further flight, replace any fuselage horizontal stabilizer attach fitting found cracked during any inspection required by paragraph (a) of this AD. Accomplish this replacement in accordance with the applicable maintenance manual.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) An alternative method of compliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, S.W., Renton, Washington 98055-4056. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(e) The inspections required by this AD shall be done in accordance with Aerostar Service Bulletin SB600-130, dated September 26, 1995. 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 the Aerostar Aircraft Corporation, Customer Service Department, South 3608 Davison Boulevard, Spokane, Washington 99204. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., 7th Floor, suite 700, Washington, DC.

(f) This amendment becomes effective on November 30, 1995.

The FAA has received a report where several cracks were found in the fuselage forward horizontal stabilizer attach spar fitting on an Aerostar Model PA-60-601P airplane. Further investigation revealed that stress corrosion caused the cracks. This airplane had been inspected for cracks in the fuselage horizontal stabilizer attach spar fittings consistently at intervals of 200 hours time-in-service (TIS).

The affected airplane had a total usage time of 4,279 hours (TIS), which is considered about average for the fleet of approximately 600 Aerostar PA-60-600 series airplanes registered in the United States. Undetected cracked fuselage horizontal stabilizer attach fittings could result in the fuselage horizontal stabilizer separating from the airplane while in flight with subsequent loss of control of the airplane.

Aerostar has issued Service Bulletin SB600-130, dated September 26, 1995, which specifies procedures for inspecting fuselage horizontalstabilizer attach fittings on Aerostar PA-60-600 series airplanes.

After examining the circumstances and reviewing all available information related to the incidents described above including the referenced service bulletin, the FAA has determined that AD action should be taken to prevent undetected cracked fuselage horizontal attach fittings, which could result in the fuselage horizontal stabilizer separating from the airplane while in flight with subsequent loss of control of the airplane.

Since an unsafe condition has been identified that is likely to exist or develop in other Aerostar PA-60-600 series airplanes of the same type design, this AD requires repetitively inspecting the fuselage horizontal stabilizer attach fittings for cracks, and replacing any cracked fuselage horizontal stabilizer attach fitting with a serviceable approved part of like design. Accomplishment of these inspections are in accordance with Aerostar Service Bulletin SB600-130, dated September 26,1995. Any fuselage horizontal stabilizer attach fitting replacement that is required shall be accomplished in accordance with the applicable maintenance manual.

The compliance time of this AD is presented in calendar time and hours TIS. Cracking of the fuselage horizontal stabilizer attach fittings on the affected airplane is caused by stress corrosion, which starts as a result of stress loads incurred through operation. Corrosion can then develop regardless of whether the airplane is in flight. The cracks may not be noticed initially as a result of the stress loads, but could then develop through corrosion. In order to ensure that these stress corrosion cracks do not go undetected, a compliance time of specific hours TIS and calendar time (whichever occurs first) is utilized.

Since a situation exists (possible separation of the fuselage horizontal stabilizer separating from the airplane during flight) that requires the immediate adoption of this regulation, it is foundthat notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 95-CE-81-AD." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation and that must be issued immediately to correct an unsafe condition in aircraft, and is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to 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:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40101, 40113, 44701.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket 95-CE-81-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.
Service information that applies to this AD may be obtained from the Aerostar Aircraft Corporation, Customer Service Department, South 3608 Davison Boulevard, Spokane, Washington 99204; telephone (509) 455-8872. This information may also be examined at the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket 95-CE-81-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Mr. Richard N. Simonson, Aerospace Engineer, Seattle Aircraft Certification Office, 1601 Lind Avenue, S.W., Renton, Washington 98055-4056; telephone (206) 227-2597; facsimile (206) 227-1181.