[Federal Register Volume 62, Number 211 (Friday, October 31, 1997)]
[Proposed Rules]
[Pages 58925-58927]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28874]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-69-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to supersede 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. The proposed AD would require 
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. The proposed 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 the proposed AD are intended to prevent failure of a flap 
system cable caused by fatigue, which could result in loss of control 
of the airplane.

DATES: Comments must be received on or before January 6, 1998.

ADDRESSES: Submit comments in triplicate to 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. Comments may be inspected at this location 
between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted.
    Service information that applies to the proposed AD may be obtained 
from the Twin Commander Aircraft Corporation, 19003 59th Drive, NE, 
Arlington, Washington 98223-7832; telephone (360) 435-9797. This 
information also may be examined at the Rules Docket at the address 
above.

FOR FURTHER INFORMATION CONTACT: 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.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report that summarizes each FAA-public contact concerned 
with the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following

[[Page 58926]]

statement is made: ``Comments to Docket No. 97-CE-69-AD.'' The postcard 
will be date stamped and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the 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.

Discussion

    AD 94-04-17, Amendment 39-8837 (59 FR 8845, February 24, 1995), 
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 certain 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. Accomplishment of the actions specified in AD 94-
04-17 is in accordance with Twin Commander Service Bulletin 210, dated 
February 1, 1991.

Actions Since Issuance of Previous Rule

    Since issuing AD 94-04-17, the FAA has received two reports of flap 
pulley assemblies with cable grooves that were too narrow. The two 
pulleys were the right inboard (slave pulley) and the right outboard 
assemblies. In addition, the FAA has received reports of discrepancies 
on flap system cables and pulleys.
    A number of pulleys were incorrectly manufactured with cable groove 
radii that are too narrow. These incorrect pulleys were produced from 
several manufacturers because the type certificate of the affected 
airplanes has been sold and transferred several times. These 
incorrectly manufactured parts include all six flap system pulleys. The 
incidents referenced in the reports affect airplanes covered by AD 94-
04-17 and airplanes not covered by AD 94-04-17. Previous compliance 
with AD 94-04-17 does not address the unsafe condition proposed in this 
NPRM because incorrectly manufactured pulleys may have been installed 
on the affected airplanes at any time before and after the issuance of 
AD 94-04-17.

Relevant Service Information

    Twin Commander has issued Service Bulletin No. 226, dated April 14, 
1997 (Revision No. 1 Release Date: July 15, 1997), which applies to all 
models of Twin Commander 500, 520, 560, 680, 681, 685, 690, 695, and 
720 series airplanes. This service bulletin specifies procedures for 
the following:

-Inspecting all flap system pulleys and cable assemblies;
-Replacing or reworking any pulley assemblies with discrepancies found 
during the inspection;
-Replacing cables, support brackets, or clips with discrepancies found 
during the inspection; and
-Identifying pulleys where the actions specified in the service 
bulletin have been accomplished

    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.

The FAA's Determination

    After examining the circumstances and reviewing all available 
information related to the incidents described above, the FAA has 
determined that AD action should be taken to prevent failure of a flap 
system cable caused by fatigue, which could result in loss of control 
of the airplane.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other 500, 520, 560, 680, 681, 685, 690, 695, and 
720 series airplanes of the same type design, the FAA is proposing an 
AD to supersede AD 94-04-17. The proposed AD would require 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 
actions would be in accordance with Twin Commander Mandatory Service 
Bulletin No. 226, dated April 14, 1997, (Revision No. 1 Release Date: 
July 15, 1997).

Cost Impact

    The FAA estimates that 1,230 airplanes in the U.S. registry would 
be affected by the proposed AD, that it would take approximately 22 
workhours per airplane to accomplish the proposed inspection, and that 
the average labor rate is approximately $60 an hour. Based on these 
figures, the total cost impact of the proposed 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 the proposed AD and do not 
reflect the costs of any repairs or replacements that may be required 
if discrepancies are found during the proposed inspection. The FAA has 
no way of determining how many parts would need to be repaired or 
replaced after accomplishing the inspection proposed in this action.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would 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) if promulgated, 
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 draft regulatory evaluation 
prepared for this action has been placed 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, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Airworthiness Directive 
(AD) 94-04-17, Amendment 39-8837 (59 FR

[[Page 58927]]

8845, February 24, 1995), and by adding a new AD to read as follows:

Twin Commander Aircraft Corporation: 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 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 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 100 hours time-in-service (TIS) after the 
effective date of this AD, accomplish 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, 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 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) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to the Twin Commander 
Aircraft Corporation, 19003 59th Drive, NE., Arlington, Washington 
98223-7832; or may examine this document at the FAA, Central Region, 
Office of the Regional Counsel, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.
    (g) This amendment supersedes AD 94-04-17, Amendment 39-8837.

    Issued in Kansas City, Missouri, on October 24, 1997.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 97-28874 Filed 10-30-97; 8:45 am]
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