AD 95-02-12

Active

Engine Mount

Key Information
95-02-12
Active
March 17, 1995
Not specified
94-NM-113-AD
39-9131
Applicability
["Aircraft"]
["Large Airplane"]
Not specified
F.28 Mark 0100
Summary

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires modification of the fixed engine cowling at the forward and aft crane beam attachment; and an inspection of the forward and aft crane beam to detect surface damage, and repair, if necessary. This amendment is prompted by several reports of rear cabin noise (engine rumble) during flight and while taxiing, which may have been caused by the interference between the forward and aft crane beams and the fasteners in the fixed engine cowling. The actions specified by this AD are intended to prevent chafing due to normal engine vibration, which could result in structural damage to the engine mount and possible separation of the engine from the airplane.

Action Required

Final rule

Regulatory Text

95-02-12 FOKKER: Amendment 39-9131. Docket 94-NM-113-AD.
Applicability: Model F28 Mark 0100 series airplanes, serial numbers 11244 through 11438 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 use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent structural damage to the engine mount and possible separation of the engine from the airplane, accomplish the following:

(a) Prior to the accumulation of 15,000 total flight hours, or within 2 years after the effective date of this AD, whichever occurs later, accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD in accordance with Fokker Service Bulletin SBF100-71-016, dated February 18, 1994.

(1) Modify the fixed engine cowling at the forward and aft crane-beam attachment in accordance with the service bulletin.

(2) Perform a visual inspection of the forward and aft crane beam to detect surface damage, in accordance with the service bulletin.

(i) If no surface damage is found, no further action is required by paragraph (a)(2) of this AD.

(ii) If any surface damage is found, prior to further flight, repair the crane beam in accordance with the 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 modification, inspection, and repair shall be done in accordance with Fokker Service Bulletin SBF100-71-016, dated February 18, 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 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 March 17, 1995.

Supplementary Information

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 F28 Mark 0100 series airplanes was published in the Federal Register on September 30, 1994 (59 FR 49865). That action proposed to require modification of the fixed cowl at the forward and aft crane-beam attachment; and performing a visual inspection of the forward and aft crane beam to detect surface damage, and repair, if necessary.

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

One commenter supports the proposed rule.

One commenter requests that the proposed 3-month "grace period" for compliance be extended to at least two years after the effective date of this AD for airplanes that are nearing or have exceeded the threshold of 15,000 flight hours. This commenter statesthat it would have to special schedule its fleet of airplanes that are approaching or have exceeded 15,000 flight hours in order to accomplish the proposed inspection/modification within the proposed compliance time. This would entail considerable additional expenses and schedule disruptions. Additionally, this commenter states that the engines on these airplanes are changed on an average of every two years and that a two-year compliance time would allow the proposed inspection/modification to be accomplished during a regularly scheduled engine change. The two-year compliance time would eliminate some of the extra down time associated with the modification. The commenter also states that no in-service incident exists to warrant such a limited compliance time.

The FAA concurs with the commenter's request. The 3-month "grace period" proposed in the notice was intended to provide additional time for compliance for those airplanes that are approaching or have exceeded 15,000 flight hours, without necessarily requiring immediate compliance (and, thus, grounding of those airplanes). The FAA selected the 3-month interval specifically as an attempt to provide as conservative an interval as possible for compliance by the higher time airplanes; however, it was selected without benefit of any empirical data or other information from the manufacturer or Dutch airworthiness authority. Based on the information provided by the commenter, and the fact that there has been no in-service incident of the subject chafing, the FAA has determined that a longer "grace period" for modification is reasonable. The FAA has revised paragraph (a) of the final rule to reflect a "grace period" of two years after the effective date of this AD. This would allow the modification to be accomplished during regularly scheduled maintenance at a main base, where special equipment and trained personnel will be available, if necessary. The FAA does not consider that this extension will adversely affect safety.

As a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been added to this final rule to clarify this requirement.

The FAA has recently reviewed the figures it has used over the past several years in calculating the economic impact of AD activity. In orderto account for various inflationary costs in the airline industry, the FAA has determined that it is necessary to increase the labor rate used in these calculations from $55 per work hour to $60 per work hour. The economic impact information, below, has been revised to reflect this increase in the specified hourly labor rate.

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 83 airplanes of U.S. registry will be affected by this AD, that it will take approximately 90 work hours per airplane to accomplish the required inspection and modification, and that the average labor rate is $60 per work hour. Required parts will cost approximately $75 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $454,425, or $5,475 per airplane.

The total 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.

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 DOTRegulatory 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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

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

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Contact Information

Tim Dulin, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2141; fax (206) 227-1320.

References
This information is not available.
--- - Part 39 [60 FR 8540 NO. 31 2/15/95]
FAA Documents