AD 96-07-04

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F27 Mark 050 and Model F28 Mark 0100 series airplanes, that requires an inspection to verify that adequate clearance exists between the insulation screen and the two adjacent terminal bolts, and replacement of the circuit breaker terminal bolts with new bolts, if necessary. This amendment is prompted by a report that circuit breaker terminal bolts that were too long were discovered installed in the circuit breaker panels. The actions specified by this AD are intended to prevent damage to the insulation screen between adjacent rows of circuit breakers, as the result of a circuit breaker terminal bolt being too long; this condition could lead to electrical arcing and loss of the associated electrical system, which could result in the potential for an electrical fire.

Final rule

96-07-04 FOKKER: Amendment 39-9553. Docket 95-NM-70-AD.
Applicability: Model F27 Mark 050 series airplanes having serial numbers 20247 through 20292 inclusive, and 20294 through 20297 inclusive; and Model F28 Mark 0100 series airplanes having serial numbers 11390 through 11479 inclusive; 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 (b) 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, unless accomplished previously.

To prevent electrical arcing and subsequent loss of the associated electrical system, which could result in the potential for an electrical fire, accomplish the following:

(a) Within 12 months after the effective date of this AD, perform an inspection to verify if adequate clearance exists between the insulation screen and the two adjacent terminal bolts in accordance with Fokker Service Bulletin SBF100-20-001, dated January 15, 1994 (for Model F28 Mark 0100 series airplanes), or Fokker Service Bulletin SBF50-20-003, dated January 11, 1994 (for Model F27 Mark 050 series airplanes), as applicable.

(1) If adequate clearance is found, no further action is required by this AD.

(2) If inadequate clearance is found, prior to further flight, replace the circuit breaker terminal bolts with new bolts in accordance with the applicable service bulletin.

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(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) The inspection and replacement shall be done in accordance with Fokker Service Bulletin SBF100-20-001, dated January 15, 1994,or Fokker Service Bulletin SBF50-20-003, dated January 11, 1994, as applicable. 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 Fokker Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on April 29, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Fokker Model F27 Mark 050 and Model F28 Mark 0100 series airplanes was published in the Federal Register on November 28, 1995 (60 FR 58584). That action proposed to require a one-time inspection to verify that adequate clearance exists between the insulation screen and the two adjacent terminal bolts, and replacement of the circuit breaker terminal bolts with new bolts, if necessary.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received.

The commenter supports the proposed rule.

After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

The FAA estimates that 44 Model F28 Mark 0100 series airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators of Model F28 Mark 0100 series airplanes is estimated to be $2,640, or $60 per airplane.

Should an operator of Model F28 Mark 0100 series airplanes be required to accomplish the necessary bolt replacement, it will take approximately 7 work hours per airplane to accomplish the replacement, at an average labor rate of $60 per work hour. Required parts will cost approximately $100 per airplane. Based on these figures, the cost impact of any necessary replacement action is estimated to be $520 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Currently there are no Fokker Model F27 Mark 050 series airplanes on the U.S. Register. However, should an affected airplane be imported and placed on the U.S. Register in the future, it will take approximately 1 work hour per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the impact of the required inspection on operators of Model F27 Mark 050 series airplanes will be $60 per airplane.

Should an operator of Model F27 Mark 050 series airplanes be required to accomplish the necessary bolt replacement, it will take approximately 17 work hours per airplane to accomplish the replacement, at an average labor rate of $60 per work hour. Required parts will cost approximately $150 per airplane. Based on these figures, the cost impact of any necessary replacement action is estimated to be $1,170 per airplane.

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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: