AD 2001-02-04

This amendment adopts a new airworthiness directive (AD) that applies to all Pilatus Aircraft LTD (Pilatus) Model PC-6 airplanes that are equipped with a certain stabilizer trim actuator. This AD requires you to inspect the lower lug of the actuator for cracks, damage, or distortion; verify that the staked bearing is correctly installed in the bore of the lug; and repair any cracked, damaged, or distorted parts and reassemble any incorrectly installed staked bearing, as necessary. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this AD are intended to detect and correct damage, distortion, or cracks in the lower lug assembly, which could result in failure of the lower lug. Such failure could lead to loss of the stabilizer trim actuator with consequent loss of control of the airplane.

Final rule

2001-02-04 PILATUS AIRCRAFT LTD.: Amendment 39-12088; Docket No. 99-CE-77-AD.

(a) What airplanes are affected by this AD? This AD affects Model PC-6 airplanes, all serial numbers, that are:

(1) certificated in any category; and

(2) equipped with a stabilizer trim actuator, part number (P/N) 978.73.18.101, 978.73.18.102, or 978.73.18.103 (Electomech P/N EM 483-1, 483-2, or 483-3), or FAA-approved equivalent part number.

(b) Who must comply with this AD? Anyone who wishes to operate any of the above airplanes must comply with this AD.

(c) What problem does this AD address? The actions specified by this AD are intended to detect and correct damage, distortion, or cracks in the lower lug assembly, which could result in failure of the lower lug. Such failure could lead to loss of the stabilizer trim actuator with consequent loss of control of the airplane.

(d) What actions must I accomplish to address this problem? To address this problem, youmust accomplish the following:

Action
Compliance Time
Procedures
(1) Inspect the lower lug of
the actuator for cracks,
damage, or distortion, and
assure that the staked bearing
is correctly installed in the bore
of the lug
.
Upon accumulating 500 hours
time-in-service (TIS) on the
airplane or within the next 100
hours TIS after March 13, 2001
(the effective date of this AD),
whichever occurs later, unless
already accomplished.
Accomplish the inspection in
accordance with the
ACCOMPLISHMENT
INSTRUCTIONS section of
Pilatus Service Bulletin No.
178, dated September 29,
1999.
(2) Repair any cracked,
damaged, or distorted parts,
as necessary, and reassemble
any incorrectly installed
staked bearing.

Prior to further flight after the
inspection required by
paragraph (d)(1) of this AD.

Accomplish any repairs in
accordance with an FAA-
approved repair scheme
obtained from the
manufacturer. Accomplishthe reassembly in accordance
with the instructions in the
maintenance manual.

(e) Can I comply with this AD in any other way? You may use an alternative method of compliance or adjust the compliance time if:

(1) Your alternative method of compliance provides an equivalent level of safety; and

(2) The Manager, Small Airplane Directorate, approves your alternative. Submit your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

Note 1: This AD applies to each airplane identified in paragraph (a) of this AD, 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 you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about any already-approved alternative methods of compliance? Contact Roman T. Gabrys, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: (816) 329-4141; facsimile: (816) 329-4090.

(g) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD.

(h) Are any service bulletins incorporated into this AD by reference? Actions required by this AD must be done in accordance with Pilatus Service Bulletin No. 178, dated September 29, 1999. The Director of the Federal Register approved this incorporation by reference under 5 U.S.C. 552(a) and 1 CFR part 51. You can get copies from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland. You can look at copies at the FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

(i) When does this amendment become effective? This amendment becomes effective on March 13, 2001.

Note 2: The subject of this AD is addressed in Swiss AD HB 99-507, dated October 1, 1999.

Discussion
What events have caused this AD? The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, recently notified the FAA that an unsafe condition may exist on all Pilatus Model PC-6 airplanes that are equipped with a stabilizer trim actuator, part number (P/N) 978.73.18.101, 978.73.18.102, or 978.73.18.103 (Electomech P/N EM 483-1, 483-2, or 483-3). The FOCA reports an incident of a cracked, damaged, and distorted lower lug of the horizontal stabilizer trim actuator. Analysis of this incident reveals that the staked bearing was loose, which caused excessive wear and failure of the actuator lower lug.

What are the consequences if the condition is not corrected? Damage, distortion, or cracks in the lower lug assembly, if not detected and corrected, could result in failure of this part. Such failure could lead to loss of the stabilizer trim actuator with consequent loss of control of the airplane.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 Pilatus Model PC-6 airplanes that are equipped with a certain stabilizer trim actuator. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on November 2, 2000 (65 FR 65789). The NPRM proposed to require you to inspect the lower lug of the actuator for cracks, damage, or distortion; verify that the staked bearing is correctly installed in the bore of the lug; and repair any cracked, damaged, or distorted parts and reassemble any incorrectly installed staked bearing, as necessary.

Was the public invited to comment? Interested persons were afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination
What is FAA's final determination on this issue? After careful review of all available information related to the subject presented above, we have 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 upon the public than was already proposed.

Cost Impact
How many airplanes does this AD impact? We estimate that this AD affects 7 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 inspection :

Labor Cost

Parts Cost
Total Cost Per
Airplane
Total Cost on US
Airplane Operators
1 workhour X $60per hour = $60
Not applicable
$60 per airplane
$60 x 7 = $420.

If any distortion, damage, or cracks are found during the inspection, you will have to repair the actuator assembly in accordance with an FAA-approved repair scheme developed by the manufacturer. The FAA has no way of determining how much incorporating each repair scheme will cost since the damage to each airplane will be unique.

Regulatory Impact
Does this AD impact various entities? The regulations adopted herein 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. Therefore, it is determined that this final rule does 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. 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, 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:

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.

39.13 [Amended]
2. FAA amends 39.13 by adding a new AD to read as follows: