AD 98-07-17 ACTIVE

This amendment supersedes Airworthiness Directive (AD) 94-04-17, which currently requires the following on Twin Commander Aircraft Corporation (Twin Commander) 500, 520, 560, 680, 681, 685, 690, 695, and 720 series airplanes: inspecting (one-time) the flap system for cables with broken wires or pulleys with worn cable clips, replacing any damaged parts, and replacing the master pulley and cable with new parts of improved design. This AD requires inspecting all flap system cable grooves for the correct width, inspecting all flap system pulleys for rubbing on the support brackets, inspecting all flap pulley cable assemblies for frayed wires, and reworking or replacing any parts with discrepancies. This AD results from several reports of worn and frayed flap system cables attributed to flap pulley grooves that are too narrow. The actions specified by this AD are intended to prevent failure of a flap system cable caused by fatigue, which could result in loss of control of the airplane.

Final rule.

98-07-17 TWIN COMMANDER AIRCRAFT CORPORATION: Amendment 39-10437; Docket No. 97-CE-69-AD. Supersedes AD 94-04-17, Amendment 39-8837.

Applicability: The following airplane models (all serial numbers), certificated in any category:

500 500-A 500-B 500-S 500-U
520 560 560-A 560-E 560-F
680 680-E 680-F 680FL 680FL(P)
680FP 680T 680V 680W 681
685 690 690A 690B 690C
690D 695 695A 695B 720

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 (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafecondition 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 a flap system cable caused by fatigue, which could result in loss of control of the airplane, accomplish the following:

(a) Within the next 300 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished, perform the following in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Twin Commander Aircraft Corporation (Twin Commander) Mandatory Service Bulletin No. 226, dated April 14, 1997 (Revision No. 1 Release Date: July 15, 1997):

(1) Inspect all flap system cable grooves for the correct width;

(2) Inspect all flap system pulleys for rubbing on the support brackets;

(3) Inspect all flap pulley cable assemblies for frayed wires; and

(4) Mark pulleys that have been inspected and have the correct groove radius with two parallel lines as specified in the service bulletin.

NOTE 2: Revision No. 1 Release Date: July 15, 1997, of Twin Commander Mandatory Service Bulletin No. 226, specifies changes in the workhours necessary to accomplish this action and makes reference to a gauge that is available from the manufacturer for use in accomplishing the inspection.

(b) If any of the above discrepancies are found, prior to further flight after the inspections required by paragraph (a), including all subparagraphs, of this AD, rework or replace the affected part in accordance with Twin Commander Mandatory Service Bulletin No. 226, dated April 14, 1997 (Revision No. 1 Release Date: July 15, 1997).

(c) As of the effective date of this AD, no person may install a pulley that does not have the criteria presented in either paragraph (c)(1), (c)(2), or (c)(3) of this AD:

(1) A pulley that has been inspected, found acceptable, and marked with two parallel lines in accordance with paragraph (a), including all subparagraphs, of this AD;

(2) A pulley that has been reworked in accordance with an FAA-approved procedure and is marked "SB 226"; or

(3) A new pulley that is marked "SB 226-NEW".

(d) 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.

(e) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Seattle Aircraft Certification Office (ACO), Northwest Mountain Region, FAA, 1601 Lind Avenue S.W., Renton, Washington 98055-4056.

(1) The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Alternative methods of compliance approved in accordance with AD 94-04-17 (superseded by this AD) are not considered approved as alternative methods of compliance for this AD.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(f) The inspections and replacements required by this AD shall be done in accordance with Twin Commander Mandatory Service Bulletin No. 226, dated April 14, 1997 (Revision No. 1 Release Date: July 15, 1997). 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 the Twin Commander Aircraft Corporation, 19003 59th Drive, NE, Arlington, Washington 98223-7832. 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.

(g) This amendment supersedes AD 94-04-17, Amendment 39-8837.

(h) This amendment becomes effective on May 29, 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 all models of Twin Commander 500, 520, 560, 680, 681, 685, 690, 695, and 720 series airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 31, 1997 (62 FR 58925). The NPRM proposed to supersede AD 94-04-17 with a new AD that requires inspecting all flap system cable grooves for the correct width, inspecting all flap system pulleys for rubbing on the support brackets, inspecting all flap pulley cable assemblies for frayed wires, and reworking or replacing any parts with discrepancies. Accomplishment of the proposed action as specified in the NPRM would be in accordance with Twin Commander Mandatory Service Bulletin No. 226, dated April 14, 1997 (Revision No. 1 Release Date: July 15, 1997).

The NPRM was the result of several reports of worn andfrayed flap system cables attributed to flap pulley grooves that are too narrow.

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

Comment Disposition

The commenter expresses concern over the availability of the parts necessary to comply with the proposed AD. The commenter states that, if the proposed AD would become a final rule with the proposed compliance time of "within the next 100 hours time-in-service (TIS) after the effective date of the AD", then the commenter's fleet of the affected airplanes would be grounded because of parts unavailability. The commenter requests that the FAA re-examine the compliance time of the proposed AD before issuing a final rule.

The FAA has re-examined the compliance time, checked with the manufacturer about the availability of parts, and has determined that a more realistic compliance time would be "within the next300 hours TIS after the effective date of this AD". The final rule reflects this change.

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 the compliance time change discussed above and minor editorial corrections. The FAA has determined that this change and 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 1,230 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 22 workhours per airplane to accomplish the inspection required by this AD, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $1,623,600, or $1,320 per airplane. These figures only take into account the inspection costs of this AD and do not reflect the costs of any repairs or replacements that may be required if discrepancies are found during the inspection. The FAA has no way of determining how many parts will need to be repaired or replaced after accomplishing the inspection.

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 Policiesand 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 removing Airworthiness Directive (AD) 94-04-17, Amendment 39-8837, and by adding a new AD to read as follows:

Service information that applies to this AD may be obtained from the Twin
Commander Aircraft Corporation, 19003 59th Drive, NE, Arlington, Washington 98223-7832. This
information may also be examined at the Federal Aviation Administration (FAA), Central Region,
Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-69-AD, Room 1558, 601 E. 12th
Street, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol
Street, NW, suite 700, Washington, DC.

Mr. Jeffrey Morfitt, Aerospace Engineer, FAA, Northwest
Mountain Region, 1601 Lind Avenue S.W., Renton, Washington 98055-4056; telephone:
(425) 227-2595; facsimile: (425) 227-1181.