AD 98-18-07

This amendment adopts a new airworthiness directive (AD) that applies to certain Pilatus Britten-Norman Ltd. (PBN) BN-2, BN-2A, BN-2B, and BN-2A MK. 111 series airplanes that are equipped with a PBN Modification NB/M/256, 50A generator system. This AD requires inspecting the airplanes that are equipped with a 50A generator system for a 70A generator. If a 70A generator is installed, this AD requires replacing the 70A generator with a 50A generator, or (for the BN-2, BN-2A, and BN-2B series only) upgrading the airplane generator system to a 70A system to match the 70A generator. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom. The actions specified by this AD are intended to detect and correct damage to the components of the electrical system, which could result in electrical system failure during critical phases of flight.

Final rule.

98-18-07 PILATUS BRITTEN-NORMAN LTD.: Amendment 39-10723; Docket No. 97-CE-111-AD. Applicability: Models BN-2, BN-2A, BN-2A-2, BN-2A-3, BN-2A-6, BN-2A-8, BN-2A-9, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN-2B-20, BN-2B-21, BN-2B-26, BN-2B-27, BN-2A MK. 111, BN-2A MK. 111-2, and BN-2A MK. 111-3 airplanes, all serial numbers, certificated in any category, that are equipped with PBN Modification NB/M/256, a 50A Generator System.

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 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 3 calendar months after the effective date of this AD, unless already accomplished.

To detect and correct damage to the components of the generator system, which could result in generator system failure during critical phases of flight, accomplish the following:

(a) Inspect the generator system for the installation of a 70A generator in accordance with the Inspection section of Pilatus Britten-Norman (PBN) Service Bulletin (SB) No. BN-2/SB.229, dated October 17, 1996.

(b) If a 70A generator is installed, accomplish the following, as applicable:

(1) For Models BN-2, BN-2A, BN-2A-2, BN-2A-3, BN-2A-6, BN-2A-8, BN-2A-9, BN-2A-20, BN-2A-21, BN-2A-26, BN-2A-27, BN-2B-20, BN-2B-21, BN-2B-26, and BN-2B-27 airplanes, prior to further flight, either:

(i) Replace the 70A generator with a 50A generator in accordance with the Replacement section of PBN SB No. BN-2/SB.229, dated October 17, 1996; or

(ii) Incorporate PBN Modification NB/M/1148 (a 70A generator system) in accordance with the appropriate Pilatus Britten-Norman maintenance manual; and, incorporate PBN Modification NB/M/1571 (installation of improved generator diodes) in accordance with PBN SB No. BN-2/228, Issue 2, dated January 17, 1996.

NOTE 2: Incorporating PBN Modification NB/M/1571 is the same action required by AD 98-04-17, Amendment 39-10329.

(2) For Models BN-2A MK. 111, BN-2A MK. 111-2, and BN-2A MK. 111-3 airplanes, prior to further flight, replace the 70A generator with a 50A generator in accordance with the Replacement section of PBN SB No. BN-2/SB.229, dated October 17, 1996.

(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 theairplane to a location where the requirements of this AD can be accomplished.

(d) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Small Airplane Directorate, 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 methods of compliance with this AD, if any, may be obtained from the Small Airplane Directorate.

(e) Questions or technical information related to PBN Service Bulletin No. BN-2/SB.229, dated October 17, 1996, or PBM Service Bulletin No. BN-2/SB.228, Issue 2, dated January 17, 1996, should be directed to Pilatus Britten-Norman, Ltd., Bembridge, Isle of Wight, United Kingdom, PO35 5PR. This service information may be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(f) The inspection, replacement, and modifications required by this AD shall be done in accordance with Pilatus Britten-Norman Service Bulletin No. BN-2/SB.229, dated October 17, 1996, or Pilatus Britten-Norman Service Bulletin No. BN-2/SB.228, Issue 2, dated January 17, 1996.

(1) The incorporation by reference of Pilatus Britten-Norman Service Bulletin No. BN-2/SB.228, Issue 2, dated January 17, 1996, was approved previously by the Director of the Federal Register as of March 23, 1997 (62 FR 4909, February 3, 1997).

(2) The incorporation by reference of Pilatus Britten-Norman Service Bulletin No. BN-2/SB.229, dated October 17, 1996, 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 Pilatus Britten-Norman. Copies may be inspected at the FAA, Central Region, Office of the Regional 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.

NOTE 4: The subject of this AD is addressed in British AD 007-10-96, not dated.

(g) This amendment becomes effective on October 12, 1998.

Events Leading to the Issuance of This AD

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain PBN BN-2, BN-2A, BN-2B, and BN-2A MK. 111 series airplanes that are equipped with a PBN Modification NB/M/256, 50A generator system, was published in the Federal Register as a notice of proposed rulemaking (NPRM) on June 9, 1998 (63 FR 31370). The NPRM proposed to require:

inspecting the airplane for a 70A generator installed on a 50A generator system;

for PBN BN-2A MK. 111 series airplanes, if a 70A generator is installed on a 50A generator system, the NPRM proposed to require replacing the 70A generator with a 50A generator;

for the BN-2, BN-2A, and BN-2B series airplanes, the NPRM proposed to require either replacing the 70A generator with a 50A generator; or upgrading the 50A generator system to a 70A generator system by incorporating PBN Modification NB/M/1148; and,if PBN Modification NB/M/1148 is incorporated, the NPRM proposed to require the incorporation of PBN Modification NB/M/1571 (which improves the diodes on the 70A generator system).

Accomplishment of the proposed actions as specified in the NPRM would be in accordance with PBN Service Bulletin No. BN-2/SB.229, dated October 17, 1996, and PBN Service Bulletin No. BN-2/SB.228, Issue 2, dated January 17, 1996.

The NPRM was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for the United Kingdom.

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 proposedexcept 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.

This Action As It Relates to Current AD's
The FAA recently issued AD 98-04-17, Amendment 39-10329 (63 FR 7696, February 17, 1998), which requires that any PBN BN-2, BN-2A, and BN-2B series airplanes that are not equipped with Modification NB/M/1571, but are equipped with PBN Modification NB/M/1148 (which incorporates the 70A generator system) should also be equipped with PBN Modification NB/M/1571. AD 98-04-17 does not affect any airplane that is equipped with a 50A generator system.

Since this AD provides an option that requires accomplishment of AD 98-04-17, the FAA is including reference of other similar AD requirements. Operators of BN-2, BN-2A, and BN-2B series airplanes that have 70A generators installed on 50A generator systems, and choose the option of upgrading their 50A generator system to a 70A generator system, will be subject to the requirements in AD 98-04-17. This AD concurrently requires installing higher amperage diodes in the 70A generator.

Pilatus Britten-Norman informed the FAA that Modification NB/M/1148 or Modification NB/M/1571 is not approved for incorporation on the BN-2A MK. 111 series airplanes.

Cost Impact
The FAA estimates that 80 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 7 workhours per airplane to accomplish this action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $500 per airplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $73,600, or $920 per airplane.

Compliance Time of This AD
The condition addressed by this AD is not caused by operation of the aircraft where the affected generators are installed. The need for the generator system modificationor replacement has no correlation to the number of times the equipment is utilized or the age of the equipment. For this reason, the compliance time of this AD is presented in calendar time instead of hours time-in-service (TIS).

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 U.S.C. 106(g), 40113, 44701.

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