Airworthiness Directives: Twin Commander Aircraft Corporation 500, 520, 560, 680, 681, 685, 690, 695, and 720 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 92-CE-59-AD; Amendment 39-8837; AD 94-04-17]

Airworthiness Directives: Twin Commander Aircraft Corporation

500, 520, 560, 680, 681, 685, 690, 695, and 720 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

applies to Twin Commander Aircraft Corporation (Twin Commander) 500,

520, 560, 680, 681, 685, 690, 695, and 720 series airplanes. This

action requires inspecting 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. Reports of cable fatigue, particularly the master pulley cable,

on several of the affected airplanes prompted this action. The actions

specified by this AD are intended to prevent flap system failure caused

by cable fatigue, which could result in loss of control of the

airplane.

DATES: Effective April 15, 1994. The incorporation by reference of

certain publications listed in the regulations is approved by the

Director of the Federal Register as of April 15, 1994.

ADDRESSES: Service information that applies to this AD may be obtained

from the Twin Commander Aircraft Corporation, 19003 59th Drive, NE.,

Arlington, Washington 98223. This information may also be examined at

the Federal Aviation Administration (FAA), Central Region, Office of

the Assistant Chief Counsel, 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.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Pasion, Aerospace Engineer,

FAA, Northwest Mountain Region, 1601 Lind Avenue SW., Renton,

Washington 98055-4056; telephone (206) 227-2594; facsimile (206) 227-

1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to include an AD that would apply to certain Twin

Commander 500, 520, 560, 680, 681, 685, 690, 695, and 720 series

airplanes was published in the Federal Register on July 19, 1993 (58 FR

38540). The action proposed to require inspecting the flap system for

cables with broken wires and pulleys with worn clips, replacing any

damaged parts, and replacing the master pulley with a new part of

improved design. The proposed actions would be accomplished in

accordance with Twin Commander Service Bulletin No. 210, dated February

1, 1991.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the two comments received.

One commenter, the Twin Commander Aircraft Corporation, supports

the proposed rule, and recommends wording the proposed AD to more

closely coincide with Service Bulletin 210, dated February 1, 1991. The

FAA concurs and has reworded the proposal accordingly. This change does

not add any additional burden upon U.S. owners/operators of the

affected airplanes than was originally proposed.

The other commenter states that a parts availability problem may

occur if owners/operators of the affected airplanes find as many

damaged pulleys in the cable system as this owner/operator did on a

Model 690B airplane. This commenter feels that there is not sufficient

parts inventory to coincide with the 50-hour time-in-service (TIS)

compliance time, and recommends changing the compliance time to 12

months. The FAA does not concur. Twin Commander has assured the FAA

that there will be adequate parts available for all required repairs.

In addition, if a temporary delay in parts availability should occur,

then an owner/operator could request an extension of the compliance

time through instructions specified in paragraph (d) of the proposed

AD. The proposed AD is unchanged as a result of this comment.

After careful review of all available information, the FAA has

determined that air safety and the public interest require the adoption

of the rule as proposed except for the wording changes referenced above

and minor editorial corrections. The FAA has determined that these

minor changes and corrections will not change the meaning of the AD nor

add any additional burden upon the public than was already proposed.

The FAA estimates that 1,860 airplanes in the U.S. registry will be

affected by this AD, that it will take approximately 25 workhours per

airplane to accomplish the required action, and that the average labor

rate is approximately $55 an hour. Parts cost approximately $600 per

airplane. Based on these figures, the total cost impact of the AD on

U.S. operators is estimated to be $3,673,500. This figure is based upon

the assumption that none of the affected airplane operators have

accomplished the required actions.

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 14 CFR part

39 of the Federal Aviation Regulations 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new AD to read

as follows:

94-04-17 Twin Commander Aircraft Corporation: Amendment 39-8837;

Docket No. 92-CE-59-AD.

Applicability: Models 500, 500A, 500B, 500S, 500U, 520, 560,

560A, 560E, 560F, 680, 680E, 680F, 680FL, 680FL(P), 680FP, 680T,

680V, 680W, 681, 685, 690, 690A, 690B, 690C, 690D, 695, 695A, 695B,

and 720 airplanes (all serial numbers), certificated in any

category:

Compliance: Required within the next 50 hours time-in-service

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

To prevent flap system failure caused by cable fatigue, which

could result in loss of control of the airplane, accomplish the

following:

(a) Accomplish the following inspections and parts replacements

(where applicable) of the flap system in accordance with the

Accomplishment Instructions section of Twin Commander Service

Bulletin (SB) No. 210, dated February 1, 1991.

(1) Rub each flap system cable over its length using a soft

cotton cloth. Where the cotton snags, visually inspect the cable for

broken wires. Prior to further flight, replace any cable having a

broken wire.

(2) Inspect the slave pulley groove width. If the groove is too

narrow as specified in Part I, paragraph C, of the Accomplishment

Instructions section of Twin Commander SB No. 210, prior to further

flight, replace the slave pulley and slave pulley cable.

(3) Visually inspect the flap system for pulleys with worn cable

clips or rubbing against the upper or lower support brackets. Prior

to further flight, replace any damaged pulleys, brackets, or clips.

(b) Replace the master pulley and the master pulley cable with

new parts of improved design in accordance with the Accomplishment

Instructions section of Twin Commander SB No. 210, dated February 1,

1991. The applicable master pulley and master cable pulley part

numbers are referenced in Table I of Twin Commander SB No. 210.

(c) Special flight permits may be issued in accordance with 14

CFR 21.197 and 21.199 to operate the airplane 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, Seattle Aircraft Certification Office

(ACO), FAA, Northwest Mountain Region, 1601 Lind Avenue SW., Renton,

Washington 98055-4056. The request shall be forwarded through an

appropriate FAA Maintenance Inspector, who may add comments and then

send it to the Manager, Seattle ACO, FAA, Northwest Mountain Region.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO, FAA, Northwest Mountain Region.

(e) The inspection and replacement required by this AD shall be

done in accordance with Twin Commander Service Bulletin No. 210,

dated February 1, 1991. 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. 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.

(f) This amendment (39-8837) becomes effective on April 15,

1994.

Issued in Kansas City, Missouri, on February 15, 1994.

Barry D. Clements,

Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 94-4127 Filed 2-23-94; 8:45 am]

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