AD 96-18-21

This amendment supersedes Airworthiness Directive (AD) 75-26-15, which currently requires repetitively inspecting the aileron mass balance clamp unit attachment for looseness on Pilatus Britten-Norman Ltd. (Pilatus Britten-Norman) BN-2A and BN2A MK. 111 series airplanes, and modifying the aileron and mass balance clamp unit if any looseness is found. The Federal Aviation Administration's policy on aging commuter-class aircraft is to eliminate or, in certain instances, reduce the number of certain repetitive short-interval inspections when improved parts or modifications are available. This action retains the repetitive inspections required by AD 75-26-15, and requires modifying the aileron and mass balance unit (at a certain time) as terminating action for the repetitive inspection requirement. The actions specified in this AD are intended to prevent failure of the aileron mass balance attachment, which could result in loss of control of the airplane.

Final rule.

96-18-21 PILATUS BRITTEN-NORMAN: Amendment 39-9748; Docket No. 96-CE-16-AD. Supersedes AD 75-26-15, Amendment 39-2464.

Applicability: Models BN-2, BN-2A, BN-2A-6, BN-2A-8, BN-2A-2, BN-2A-9, BN-2A-3, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN2A MK. 111, BN2A MK. 111-2, and BN2A MK. 111-3 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 (f) 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 as indicated in the body of this AD, unless already accomplished.

To prevent failure of the aileron mass balance attachment, which could result in loss of control of the airplane, accomplish the following:

(a) Prior to the first flight of each day after the effective date of this AD (see NOTE 2 of this AD), inspect the attachment of the aileron mass balance clamp unit for looseness in accordance with the "Inspection" section of Britten-Norman Service Bulletin (SB) No. BN-2/SB.67, Issue 1, dated October 24, 1973.

NOTE 2: The "prior to first flight of each day after the effective date of this AD" compliance time required by paragraph (a) of this AD is exactly the same as required by AD 75-26-15 (superseded by this AD).

(b) If a loose attachment of the aileron mass balance clamp unit is found during any of the inspections required by this AD, prior to further flight, modify the aileron and mass balance clamp unit in accordance with the "b. Sequence of Operations" section of Britten-Norman SB No. BN-2/SB.67, Issue 1, dated October 24, 1973.

(c) Within the next 1,000 hours time-in-service after the effective date of this AD, unless already accomplished as specified and required by paragraph (b) of this AD, modify the aileron and mass balance clamp unit in accordance with the "b. Sequence of Operations" section of Britten-Norman SB No. BN-2/SB.67, Issue 1, dated October 24, 1973.

(d) Accomplishing the modification required by paragraph (b) or (c) of this AD is considered terminating action for the repetitive inspection requirement of this AD.

(e) 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.

(f) An alternative method ofcompliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Brussels Aircraft Certification Division, Europe, Africa, Middle East office, FAA, c/o American Embassy, 1000 Brussels, Belgium. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Brussels Aircraft Certification Division. Alternative methods of compliance approved in accordance with AD 75-26-15 (superseded by this action) are not considered approved as alternative methods of compliance with this AD.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Brussels Aircraft Certification Division.

(g) The inspections and modification required by this AD shall be done in accordance with Britten-Norman Service Bulletin No. BN-2/SB.67, Issue 1, dated October 24, 1973.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 Pilatus Britten-Norman Limited, Bembridge, Isle of Wight, United Kingdom PO35 5PR. 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., suite 700, Washington, DC.

(h) This amendment (39-9748) supersedes AD 75-26-15, Amendment 39-2464.

(i) This amendment becomes effective on October 25, 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 Britten-Norman BN-2A and BN2A MK. 111 series airplanes was published in the Federal Register on May 9, 1996 (61 FR 21146). The action proposed to supersede AD 75-26-15 with a new AD that would (1) retain the requirements of repetitively inspecting the aileron mass balance clamp unit attachment for looseness and modifying any aileron and mass balance unit immediately where looseness is found; and (2) require modifying the aileron and mass balance unit (at a certain time) if not previously required. The modification would terminate the need for the repetitive inspections of the aileron and mass balance unit attachment. Accomplishment of the proposed actions would continue to be in accordance with Britten-Norman Service Bulletin No. BN-2/SB.67, Issue 1, dated October 24, 1973.

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 determination of the cost to the public.

The 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 109 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 10 workhours (inspection: 1 workhour; modification: 9 workhours) per airplane to accomplish the action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $160 per airplane. Based on these figures, thetotal cost impact of this AD on U.S. operators is estimated to be $82,840. This figure only takes into account the cost of the initial inspection and inspection-terminating modification and does not take into account the cost of repetitive inspections. The FAA has no way of determining the number of repetitive inspections each of the owners/operators will incur over the life of the affected airplanes.

This figure is also based on the assumption that no affected airplane owner/operator has accomplished the required modification. This action eliminates the repetitive inspections required by AD 75-26-15. The FAA has no way of determining the operational levels of each individual operator of the affected airplanes, and subsequently cannot determine the repetitive inspection costs that would be eliminated by this action. The FAA estimates these costs to be substantial over the long term.

Pilatus Britten-Norman does not know the number of parts distributed to the affected airplane owners/operators. Numerous sets of parts were sent out to the owners/operators of the affected airplanes, but over the years Pilatus Britten-Norman has not retained these records. The company believes that most of the affected airplanes already have the required inspection-terminating modification incorporated.

The FAA's Aging Commuter Class Aircraft Policy
This AD is part of the FAA's aging commuter airplane policy, which briefly states that, when a modification exists that could eliminate or reduce the number of required critical inspections, the modification should be incorporated.

The intent of the FAA's aging commuter airplane program is to ensure safe operation of airplanes that are in commercial service without adversely impacting private operators. Of the approximately 109 airplanes in the U.S. registry that would be affected by this AD, the FAA has determined that approximately 25 percent are operated in scheduled passenger service by 11 different operators. Asignificant number of the remaining 75 percent are operated in other forms of air transportation such as air cargo and air taxi.

This action allows 1,000 hours time-in-service (TIS) after the effective date of the AD before mandatory accomplishment of the design modification. The average utilization of the fleet for those airplanes in commercial commuter service is approximately 25 to 50 hours TIS per week. Based on these figures, operators of airplanes involved in commercial operation will have to accomplish the modification within 5 to 10 months after this AD becomes effective. For private owners, who typically operate between 100 to 200 hours TIS per year, this allows 5 to 10 years before the required modification becomes mandatory. The time it would take those in air cargo/air taxi operations before this action becomes mandatory is unknown because of the wide variation between each airplane used in this service. The exact numbers would fall somewhere between the average for commuter operators and private operators.

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 containedin 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 removing Airworthiness Directive (AD) 75-26-15, Amendment 39-2464, and by adding a new AD to read as follows: