[Federal Register Volume 60, Number 22 (Thursday, February 2, 1995)]
[Proposed Rules]
[Pages 6459-6461]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2406]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-CE-29-AD]


Airworthiness Directives; Twin Commander Aircraft Corporation 
Models 690C and 695 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Twin Commander Aircraft Corporation 
(Twin Commander) Models 690C and 695 airplanes. The proposed action 
would require initially inspecting the wing structure for cracks, 
modifying any cracked wing structure, and, if not cracked, either 
repetitively inspecting or modifying the wing structure. Results of 
full-scale fatigue testing that indicated areas in the wing that are 
subject to fatigue cracks prompted the proposed action. The actions 
specified by the proposed AD are intended to prevent wing damage caused 
by fatigue cracking, which, if not detected and corrected, could 
progress to the point of structural failure.

DATES: Comments must be received on or before April 9, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 94-CE-29-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, 19010 59th Drive, NE, 
Arlington, Washington 98223. This information also may be examined at 
the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Mr. Mike Pasion, Aerospace Engineer, 
FAA, Northwest Mountain Region, 1601 Lind Avenue S.W., Renton, 
Washington 98055-4056; telephone (206) 227-2594; facsimile (206) 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 

[[Page 6460]]
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 statement is made: ``Comments 
to Docket No. 94-CE-29-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 Assistant Chief Counsel, 
Attention: Rules Docket No. 94-CE-29-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Discussion

    Recently, the FAA become aware of an unsafe condition that could 
exist on Twin Commander Models 690C and 695 airplanes. Full-scale 
fatigue testing of the wing and the wing carry-through and pressure 
vessel structures has revealed that these areas are susceptible to 
fatigue cracking.
    Twin Commander has issued Service Bulletin (SB) No. 213, dated July 
29, 1994, which specifies procedures for inspecting and modifying the 
wing structure.
    After examining the circumstances and reviewing all available 
information related to the test results described above, including the 
referenced service information, the FAA has determined that AD action 
should be taken to prevent wing damage caused by fatigue cracking, 
which, if not detected and corrected, could progress to the point of 
structural failure.
    Since an unsafe condition has been identified that is likely to 
exist or develop in other Twin Commander Models 690C and 695 airplanes, 
the proposed AD would require initially inspecting the wing structure 
for cracks, modifying any cracked wing structure, and, if not cracked, 
either repetitively inspecting or modifying the wing structure. The 
proposed actions would be accomplished in accordance with Twin 
Commander SB No. 213, dated July 29, 1994.
    The FAA is establishing the compliance time of the proposed initial 
and first repetitive inspection to coincide with the 6,000-hour Major 
Inspection Guide I and 7,500-hour Major Inspection Guide II 
inspections, respectively.
    The FAA estimates that 86 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 66 
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 $320,560. This figure does not take into account the 
cost of repetitive inspections or the cost of any modifications that 
may be needed based on the inspection results. The FAA has no way of 
determining how many wing structures may be cracked and need 
modification, or how many repetitive inspections each owner/operator 
may incur over the life of the airplane.
    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 
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.
Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new AD to read as follows:

Twin Commander Aircraft Corporation: Docket No. 94-CE-29-AD.

    Applicability: The following airplane models and serial numbers, 
certificated in any category:

------------------------------------------------------------------------
                    Model                             Serial No.        
------------------------------------------------------------------------
690C........................................  11600 through 11735.      
695.........................................  95000 through 95084.      
------------------------------------------------------------------------

    Compliance: Required upon the accumulation of 6,000 hours time-
in-service (TIS) or within the next 50 hours TIS after the effective 
date of this AD, whichever occurs later, unless already 
accomplished, and thereafter as indicated in the body of this AD.
    To prevent wing damage caused by fatigue cracking, which, if not 
detected and corrected, could progress to the point of structural 
failure, accomplish the following:
    (a) For all affected serial number Model 695 airplanes, and any 
Model 690C airplane incorporating a serial number in the 11600 
through 11730 range, inspect the wing structure for cracks in 
accordance with the PART I ACCOMPLISHMENT INSTRUCTIONS (INSPECTIONS) 
section of Twin Commander Service Bulletin (SB) No. 213, dated July 
29, 1994.
    (b) For any Model 690C airplane incorporating a serial number in 
the 11731 through 11735 range, inspect the wing structure for cracks 
in accordance with Item 10 of the PART I ACCOMPLISHMENT INSTRUCTIONS 
(INSPECTIONS) section of Twin Commander SB No. 213, dated July 29, 
1994.
    (c) If, during the inspections required in paragraphs (a) and 
(b) of this AD, cracks are found in the areas referenced in Figures 
1 through 5 and the instructions of the service information 
referenced above, prior to further flight, replace the damaged 
structure and modify the wing structure in accordance with the PART 
II ACCOMPLISHMENT INSTRUCTIONS (MODIFICATIONS) section of Twin 
Commander SB No. 213, dated July 29, 1994.
    (d) If no cracks are found, accomplish one of the following:
    (1) For all airplanes, upon the accumulation of 7,500 hours TIS 
or within 

[[Page 6461]]
1,000 hours TIS after the initial inspection, whichever occurs later, 
reinspect the structure in accordance with either paragraph (a) or 
(b) of this AD, as applicable, and reinspect thereafter at intervals 
not to exceed 1,000 hours TIS, and, if applicable, replace any 
damaged part or modify the wing structure as specified in paragraph 
(c) of this AD; or
    (2) For Model 695 airplanes and any Model 690C airplane 
incorporating a serial number in the 11600 through 11730 range, 
prior to further flight, modify the wing structure in accordance 
with the PART II ACCOMPLISHMENT INSTRUCTIONS (MODIFICATIONS) section 
of Twin Commander SB No. 213, dated July 29, 1994.
    (e) For Model 695 airplanes and any Model 690C airplane 
incorporating a serial number in the 11600 through 11730 range, the 
modification referenced in paragraphs (c) and (d)(2) of this AD may 
be accomplished any time after the initial inspection as terminating 
action for the repetitive inspection requirement of this AD, except 
for the inspection of the doublers at the wing attach fittings 
located in the Fuselage Station 144 frame (Item 10 of PART I 
ACCOMPLISHMENT INSTRUCTIONS (INSPECTIONS) section of the Twin 
Commander SB No. 213, dated July 29, 1994. All affected model and 
serial number airplanes must inspect in this area at every 1,000 
hours TIS.

    Note 1: For those airplanes that have not accumulated 6,000 
hours TIS, the initial and first repetitive inspection required by 
this AD were established to coincide with the 6,000-hour Major 
Inspection Guide I and 7,500-hour Major Inspection Guide II 
inspections, respectively, so that the operator may schedule the 
required action in accordance with these major inspections.

    (f) 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.
    (g) 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 S.W., 
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.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (h) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to the Twin Commander 
Aircraft Corporation, 19010 59th Drive, NE., Arlington, Washington 
98223; or may examine this document at the FAA, Central Region, 
Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri 64106.

    Issued in Kansas City, Missouri, on January 26, 1995.
Michael K. Dahl,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-2406 Filed 2-1-95; 8:45 am]
BILLING CODE 4910-13-U