AD 96-22-13

This amendment adopts a new airworthiness directive (AD) that applies to Pilatus Aircraft Ltd. (Pilatus), Model PC-6 airplanes. This action requires inspecting for loose or sheared rivets in the hinge brackets on the horizontal stabilizer and inspecting for incorrect spacing tolerance of the hinge brackets. If the rivets are found loose or sheared, the AD requires replacing the rivets and also re-positioning the hinge brackets, if found incorrectly spaced. Several reports of rivets shearing on the hinge brackets prompted this action. The actions specified by this AD are intended to prevent structural failure of the hinge bracket on the horizontal stabilizer, which could result in partial or complete loss of control of the horizontal stabilizer and loss of control of the airplane.

Final rule.

96-22-13 PILATUS AIRCRAFT LTD.: Amendment 39-9801; Docket No. 95-CE-85-AD.

Applicability: Model PC-6 airplanes, (all serial numbers), certificated in any category.

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 (e) of this AD. The request should include an assessment of the effect of the 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 within the next 75 hours time-in-service (TIS), after the effective date of this AD, unless already accomplished.

NOTE 2: The compliance time required in this AD takes precedence over the compliance time in Pilatus Service Bulletin PC-6 165, dated February 7, 1994.

To prevent structural failure of the hinge bracket on the horizontal stabilizer, which could result in partial or complete loss of control of the horizontal stabilizer and loss of control of the airplane, accomplish the following:

(a) Inspect the hinge brackets on the horizontal stabilizer for sheared or loose rivets in accordance with paragraph 2.A. in the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin (SB) PC-6 165, dated February 7, 1994.

(b) Inspect the spacing tolerance of the hinge bracket in accordance with paragraph 2.C. in the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus SB PC-6 165, dated February 7, 1994.

(c) If there are loose or sheared rivets or if the bracket spacing is out of the spacing tolerance, prior to further flight,modify the position and space tolerance of the hinge brackets, and replace any loose or sheared rivets in accordance with paragraph 2.D. in the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus SB PC-6 165, dated February 7, 1994.

(d) 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.

(e) An alternative method of compliance or adjustment of the compliance times that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, Aircraft Certification Service, FAA, 1201 Walnut, suite 900, Kansas City, Missouri 64106. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

NOTE 3: Information concerning the existence of approved alternative methodsof compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(f) The inspection, modification, and replacement required by this AD shall be done in accordance of Pilatus Service Bulletin PC-6 165, dated February 7, 1994. 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 of this document may be obtained from Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. Copies also 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., suite 700, Washington, DC.

(g) This amendment becomes effective on December 27, 1996.

Events Leading to This Action

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to Pilatus Model PC-6 airplanes was published in the Federal Register on June 11, 1996 (61 FR 29501). The action proposed to require the following:

-- Inspecting the hinge brackets attached to the fuselage for loose or sheared rivets,

-- Inspecting the hinge brackets for correct spacing tolerance and positioning,

-- Removing the brackets and adjusting any incorrect spacing or positioning, and

-- Replacing any loose or sheared rivets with new rivets. Related Service Information

Accomplishment of this action would be in accordance with Pilatus Service Bulletin (SB) PC-6 165, dated February 7, 1994.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determinationof the cost to the public.

FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact
The FAA estimates that one airplane in the U.S. registry will be affected by this AD, that it will take less than 1 workhour per airplane to accomplish these actions, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of this AD for the only U.S. operator is estimated to be $60. This is the cost of the inspection only and does not include the cost for replacing any loose rivets, if found. This figure is based on the assumption that the affected owner/operator of the affected airplane has not performed the inspection or modification.

Regulatory Impact
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.

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. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".

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), 40113, 44701.

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