[Federal Register Volume 59, Number 35 (Tuesday, February 22, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3836]


[[Page Unknown]]

[Federal Register: February 22, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 92-CE-43-AD; Amendment 39-8833; AD 94-04-13]

 

Airworthiness Directives: Twin Commander Aircraft Corporation 
500, 600, and 700 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes Airworthiness Directive (AD) 65-06-
01, which currently requires repetitively inspecting the wing front 
spar lower cap (spar cap) of both the left and right wings on certain 
Twin Commander Aircraft Corporation (Twin Commander) 500 and 600 series 
airplanes, and replacing any cracked spar cap. Front spar cap cracks 
developing on certain Twin Commander model airplanes not affected by 
that AD prompted this action. In addition, the manufacturer has updated 
the inspection procedures through improved service information. This 
action retains the inspection and repair requirements of AD 65-06-01, 
and requires inspecting in accordance with updated service information 
and increases the applicability to include other model airplanes. The 
actions specified by this AD are intended to prevent failure of the 
wing structure caused by cracks in the spar cap.

DATES: Effective April 12, 1994.
    The incorporation by reference of Twin Commander Service Bulletin 
(SB) No. 90C, dated March 30, 1992, and Twin Commander Service 
Publications revision notice of SB 90C, Revision 1, dated June 5, 1992, 
is approved by the Director of the Federal Register as of April 12, 
1994.
    The incorporation by reference of the instructions to Twin 
Commander Custom Kit No. CK-145, dated August 21, 1992, was previously 
approved by the Director of the Federal Register as of April 11, 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, 600, and 700 series airplanes was published in the 
Federal Register on June 30, 1993 (58 FR 34955). The action proposed to 
supersede AD 65-06-01 with a new AD that would (1) retain the 
inspection and repair requirements of the spar caps required by AD 65-
06-01; (2) incorporate the updated service information into the 
proposed AD; and (3) increase the effectivity of the current AD to 
include other airplane models of the Twin Commander 500, 600, and 700 
series. The proposed inspections would be accomplished in accordance 
with Twin Commander SB No. 90C, dated March 30, 1992, and Twin 
Commander Service Publications revision notice of SB No. 90C, Revision 
1, dated June 5, 1992.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the 10 comments received.
    Nine commenters concur with the proposal as written.
    Twin Commander supports the proposal and makes recommendations. 
Twin Commander states that the Compliance section of the proposal 
contains the following: ``* * * or 500 hours after the wing front lower 
spar cap was replaced in accordance with one of the three modifications 
referenced in paragraph (b) of this AD * * *'', and points out that 
paragraph (b) of this AD only specifies two modifications and that the 
wording in the Compliance section of the proposal should be changed 
accordingly. The FAA concurs and has changed the proposed AD by 
inserting the words ``in accordance with one of the two modifications'' 
in place of ``in accordance with one of the three modifications'' under 
the Compliance section.
    Twin Commander also states that the proposed AD should include the 
Model 680F(P) airplanes in the applicability to coincide with SB 90C. 
The FAA concurs that these airplanes should be included. Adding this 
airplane model to the applicability goes beyond the scope of what was 
originally proposed, and would obligate the FAA to issue a supplemental 
notice of proposed rulemaking (NPRM) to allow additional time for the 
public to comment. The FAA has determined that the additional comment 
time is unnecessary for the model airplanes included in the 
applicability of the proposed AD, and, after the proposed rule becomes 
final, the FAA will issue an NPRM to add the Model 680F(P) airplanes 
into the applicability of that AD. The proposed rule is unchanged as a 
result of this comment.
    After careful review of all available information including the 
comments referenced above, the FAA has determined that air safety and 
the public interest require the adoption of the rule as proposed except 
for the minor wording change and other minor editorial corrections. The 
FAA has determined that these minor 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 1,303 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 32 (average) 
workhours per airplane to accomplish the required action, and that the 
average labor rate is approximately $55 an hour. Parts are not required 
for 1,054 airplanes, and parts cost approximately $700 per airplane for 
105 airplanes and $1,700 per airplane for 144 airplanes. Based on these 
figures, the total cost impact of the inspections specified in this AD 
on U.S. operators is estimated to be $2,611,580 (cost per airplane 
varies by model).
    AD 65-06-01 currently requires the same actions as this AD on 1,025 
of 1,303 airplanes. Of the remaining 307 airplanes affected by this AD, 
the FAA estimates that it will take approximately 18 workhours for 156 
airplanes and 100 workhours for 151 airplanes, depending upon the 
particular model. Parts are not required for 156 airplanes and cost 
approximately $1,700 for 151 airplanes. Based on these figures, the 
cost impact of this AD upon U.S. operators not already affected by AD 
65-06-01 is approximately $1,241,640 (cost per airplane varies by 
model).
    In addition, if the required inspection reveals cracks in the spar 
cap, replacing the spar cap is required at a cost of approximately 
$100,000, parts and labor included. An airplane affected by this AD 
could have a compliance cost as low as approximately $990 (18 
workhours) or $7,200 (100 workhours) if cracks were not found during 
the inspection, and as high as approximately $100,990 (inspection using 
18 workhours + spar replacement) to $107,200 (inspection using 100 
workhours + spar replacement) if the operator replaces the spar cap.
    The FAA estimates that the airplanes affected by the required AD 
are utilized an average of approximately 200 hours time-in-service per 
year, or an average time-interval between the required inspections of 
2.5 years.
    Based on an expected average remaining operating life of 20 years 
per affected airplane, the annualized compliance cost would be:
     If only repetitively inspecting the spar cap is necessary 
at 18 workhours: $456 annualized cost (using a 7 percent interest 
rate);
     If only repetitively inspecting the spar is necessary at 
100 workhours: $2,700 annualized cost (using a 7 percent interest 
rate); or
     If replacing the spar cap is necessary: approximately 
$9,971 annualized cost (with 18 workhours for inspection and using a 7 
percent interest rate) and $10,372 annualized cost (with 100 workhours 
for inspection and using a 7 percent interest rate) if the spar cap is 
replaced during the first inspection.
    The required AD's from Dockets No. 92-CE-26-AD (for Model 500S), 
No. 92-CE-57-AD (for Models 500, 560A, 560E, 680, 680E, and 720), and 
No. 92-CE-58-AD (for Models 500S, 500U, 680FL, 680W, and 681), also 
affect certain airplanes included in this AD. The compliance costs of 
these AD's add to the cost discussed above. However, replacing the spar 
cap is only required once, so the $100,000 replacement cost, if 
required, would be a one-time action.
    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to ensure that small entities are not unnecessarily or 
disproportionally burdened by government regulations. The RFA requires 
government agencies to determine whether rules would have a 
``significant economic impact on a substantial number of small 
entities,'' and, in cases where they would, conduct a Regulatory 
Flexibility Analysis in which alternatives to the rule are considered. 
FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance, 
outlines FAA procedures and criteria for complying with the RFA. Small 
entities are defined as small businesses and small not-for-profit 
organizations that are independently owned and operated or airports by 
small governmental jurisdictions.
    The 307 U.S.-registered airplanes affected by this AD that are not 
already affected by AD 65-06-01 are owned according to the following 
breakdown: 80 by individuals, 3 by U.S. government agencies, 9 by 
states or local governments, and 215 by other entities. Four entities 
own more than one of the affected airplanes that are not affected by AD 
65-06-01: two own 2 each, and two own 5 each. Three entities own models 
that will be affected by this AD, as well as AD 65-06-01.
    The FAA cannot determine the sizes of all the affected non-
individual owner entities nor the relative significance of the costs 
estimated above. Because of these uncertainties, no cost thresholds for 
significant economic impact can be reasonably determined. The FAA 
solicited comments concerning the impact of the NPRM on owners of 
affected airplanes, and received no comments on this matter. Based on 
the possibility that this AD could have a significant impact on a 
substantial number of small entities, the FAA conducted a regulatory 
flexibility analysis. A copy of this analysis may be obtained by 
contacting the Rules Docket at the location provided under the caption 
``ADDRESSES''.
    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 significant under DOT Regulatory Policies and Procedures (44 FR 
11034, February 26, 1979) because of substantial public interest; and, 
(3) if promulgated, may have a significant economic impact on a 
substantial number of small entities. The FAA has conducted an Initial 
Regulatory Flexibility Determination and Analysis and has considered 
alternatives to this action that could minimize the impact on small 
entities. A copy of this analysis may be obtained by contacting the 
Rules Docket at the location provided under the caption ``ADDRESSES''. 
After careful consideration, the FAA has determined that the required 
action is the best course to achieve the safety objective of returning 
the airplane to its original certification level of safety.

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 removing AD 65-06-01, Amendment 39-
1053, and by adding the following new airworthiness directive to read 
as follows:

94-04-13 Twin Commander Aircraft Corporation: Amendment 39-8833; 
Docket No. 92-CE-43-AD. Supersedes AD 65-06-01, Amendment 39-1053.

    Applicability: All serial numbers of the following model 
airplanes, certificated in any category: 500, 500A, 500B, 500S, 
500U, 520, 560, 560A, 560E, 560F, 680, 680E, 680F, 680FL(P), 680FL, 
680T, 680V, 680W, 681, and 720.
    Compliance: Required initially within the next 50 hours time-in-
service (TIS), unless already accomplished (compliance with 
superseded AD 65-06-01), or 500 hours after the wing from lower spar 
cap was replaced in accordance with one of the two modifications 
referenced in paragraph (b) of this AD, whichever occurs later, and 
thereafter at intervals not to exceed 500 hours TIS.

    Note 1: Although not required, it is recommended that airplanes 
utilized for survey usage and low altitude usage (below 1,000 feet 
AGL) reinspect at more periodic intervals described below and 
specified in Twin Commander Service Publications revision notice of 
Service Bulletin No. 90C, Revision 1, dated June 5, 1992: 

------------------------------------------------------------------------
                                                                  Hours 
                             Usage                                 TIS  
------------------------------------------------------------------------
Survey.........................................................      200
Low Altitude...................................................      100
------------------------------------------------------------------------

    To prevent failure of the wing structure caused by cracks in the 
lower front spar cap, accomplish the following:
    (a) Inspect the wing front spar lower cap at left and right Wing 
Station 24 in accordance with the instructions in the applicable 
part of Twin Commander SB No. 90C, dated March 30, 1992, and Twin 
Commander Service Publications revision notice of SB No. 90C, 
Revision 1, dated June 5, 1992. The applicable part of the 
referenced service bulletin is outlined below:
    (1) Part I: Models 500, 500A, 500B, 500S, 500U, 520, 560, 560A, 
560E, 560F, 680, 680E, 680F, 680F(P), and 720 airplanes.
    (2) Part II: Models 680FL and 680FL(P) airplanes.
    (3) Part III: Models 680FL, 680FL(P), 680T, 680V, 680W, and 681 
airplanes.
    (b) If cracks are found, prior to further flight, replace the 
wing front spar lower cap in accordance with one of the following, 
as applicable:
    (1) For models 500S, 500U, 680FL, 680FL(P), 680W, and 681--the 
instructions in Twin Commander Custom Kit No. CK-145, dated August 
21, 1992; or
    (2) For models 500, 500A, 500B, 520, 560, 560A, 560E, 560F, 
680E, 680F, 680T, 680V, 680W, and 720--obtain replacement procedures 
from the manufacturer through the Manager, Seattle Aircraft 
Certification Office, at the address specified in paragraph (d) of 
this AD.
    (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 
initial and repetitive compliance times 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 2: 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 inspections required by this AD shall be done in 
accordance with Twin Commander Service Bulletin No. 90C, dated March 
30, 1992, and Twin Commander Service Publications revision notice of 
Service Bulletin No. 90C, Revision 1, dated June 5, 1992. 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. The replacement (as applicable) required by this AD shall be 
done in accordance with the instructions to Twin Commander Custom 
Kit No. CK-145, dated August 21, 1992. This incorporation by 
reference was previously approved as of April 11, 1994, 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 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 (39-8833) supersedes AD 65-06-01, Amendment 
39-1053.
    (g) This amendment (39-8833) becomes effective on April 12, 
1994.

    Issued in Kansas City, Missouri, on February 14, 1994.
Barry D. Clements,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 94-3836 Filed 2-18-94; 8:45 am]
BILLING CODE 4910-13-U