[Federal Register Volume 60, Number 21 (Wednesday, February 1, 1995)]
[Proposed Rules]
[Pages 6045-6047]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2407]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-CE-27-AD]


Airworthiness Directives; Twin Commander Aircraft Corporation 
685, 690, and 695 Series 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) 685, 690, and 695 series airplanes. The proposed 
action would require initially inspecting the vertical stabilizer for 
cracks, modifying any cracked vertical stabilizer, and, if not cracked, 
either repetitively inspecting or modifying the vertical stabilizer. 
Several reports of the vertical stabilizer cracking in different areas 
prompted the proposed action. The actions specified by the proposed AD 
are intended to prevent failure of the vertical stabilizer as a result 
of cracking, which, if not detected and corrected, could result in loss 
of control of the airplane.

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-27-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, N.E., 
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 
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-27-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-27-AD, Room [[Page 6046]] 1558, 601 
E. 12th Street, Kansas City, Missouri 64106.

Discussion

    The FAA has received several reports of damaged vertical 
stabilizers on certain Twin Commander Models 685, 690, 690A, 690B, 
690C, 690D, 695, and 695A airplanes. Specifically, these reports 
include: cracks in the lower ribs, wrinkles and cracks in the skin near 
the lower ribs, cracked spar clips between the lower ribs and the rear 
spar, and cracks in the upper relief cutouts of the Fuselage Station 
409.56 bulkhead.
    Twin Commander has issued Service Bulletin (SB) No. 218, dated May 
19, 1994, including Revision Notices 1 and 2, dated July 11, 1994, and 
September 23, 1994, respectively. This service information specifies 
procedures for inspecting and modifying the vertical stabilizer.
    After examining the circumstances and reviewing all available 
information related to the incidents described above, including the 
referenced service information, the FAA has determined that AD action 
should be taken to prevent failure of the vertical stabilizer as a 
result of cracking, which, if not detected and corrected, could result 
in loss of control of the airplane.
    Since an unsafe condition has been identified that is likely to 
exist or develop in other Twin Commander Models 685, 690, 690A, 690B, 
690C, 690D, 695, and 695A airplanes, the proposed AD would require 
initially inspecting the vertical stabilizer for cracks, modifying any 
cracked vertical stabilizer, and, if not cracked, either repetitively 
inspecting or modifying the vertical stabilizer. The proposed actions 
would be accomplished in accordance with Twin Commander SB No. 218, 
dated May 19, 1994, including Revision Notices 1 and 2, dated July 11, 
1994, and September 23, 1994, respectively.
    The FAA estimates that 469 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 10 
workhours per airplane to accomplish the proposed inspection, and that 
the average labor rate is approximately $60 an hour. Parts to 
accomplish the proposed inspection cost approximately $200 per 
airplane. Based on these figures, the total cost impact of the proposed 
AD on U.S. operators is estimated to be $375,200. 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 vertical stabilizers may be 
cracked and need modification, or how many repetitive inspections each 
owner/operator may incur.
    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-27-AD.

    Applicability: The following airplane models and serial numbers, 
certificated in any category that have not modified the vertical 
stabilizer in accordance with the ACCOMPLISHMENT INSTRUCTIONS: PART 
II--MODIFICATION section of Twin Commander Service Bulletin (SB) No. 
218, dated May 19, 1994, including Revision Notices 1 and 2, dated 
July 11, 1994, and September 23, 1994, respectively:

------------------------------------------------------------------------
                    Model                             Serial Nos.       
------------------------------------------------------------------------
685.........................................  12000 through 12066.      
690.........................................  11000 through 11079.      
690A........................................  11100 through 11344.      
690B........................................  11350 through 11566.      
690C........................................  11600 through 11735.      
690D........................................  15001 through 15042.      
695.........................................  95000 through 95084.      
695A........................................  96001 through 96100.      
------------------------------------------------------------------------

    Compliance: Required upon the accumulation of 2,000 hours time-
in-service (TIS) on a vertical stabilizer 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 failure of the vertical stabilizer as a result of 
cracks, which, if not detected and corrected, could result in loss 
of control of the airplane, accomplish the following:
    (a) Inspect the vertical stabilizer for cracks in accordance 
with the ACCOMPLISHMENT INSTRUCTIONS: PART I--INSPECTION section of 
Twin Commander SB No. 218, dated May 19, 1994, including Revision 
Notices 1 and 2, dated July 11, 1994, and September 23, 1994, 
respectively.
    (b) If damage or cracks are found within the limits of Figures 1 
and 2 of the service information referenced above, prior to further 
flight, modify the vertical stabilizer in accordance with the 
ACCOMPLISHMENT INSTRUCTIONS: PART II--MODIFICATION section of Twin 
Commander SB No. 218, dated May 19, 1994, including Revision Notices 
1 and 2, dated July 11, 1994, and September 23, 1994, respectively.
    (c) If damage or cracks are found outside the limits referenced 
in Figures 1 and 2 of the service information referenced above or if 
cracks intersect, prior to further flight, replace the damaged parts 
with new parts in accordance with the applicable maintenance manual 
instructions. The requirements of this AD still apply when the 
damaged parts are replaced, unless the stabilizer is modified as 
specified in paragraph (b) of this AD.
    (d) If no cracks are found, accomplish one of the following:
    (1) Reinspect at intervals not to exceed 500 hours TIS, and 
modify any damaged or cracked vertical stabilizer as specified in 
paragraphs (b) and (c) of this AD; or
    (2) Prior to further flight, modify the vertical stabilizer in 
accordance with the ACCOMPLISHMENT INSTRUCTIONS: PART II--
MODIFICATION section of Twin Commander SB No. 218, dated May 19, 
1994, including Revision Notices 1 and 2, dated July 11, 1994, and 
September 23, 1994, respectively.
    (e) Special flight permits may be issued in accordance with 
Secs. 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.
    (f) 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 [[Page 6047]] request shall be 
forwarded through an appropriate FAA Maintenance Inspector, who may 
add comments and then send it to the Manager, Seattle ACO.

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

    (g) 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; 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. 95-2407 Filed 1-31-95; 8:45 am]
BILLING CODE 4910-13-U