Federal Register, Volume 62 Issue 160 (Tuesday, August 19, 1997)

[Federal Register Volume 62, Number 160 (Tuesday, August 19, 1997)]
[Proposed Rules]
[Pages 44096-44099]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-21873]

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Proposed Rules
Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.

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Federal Register / Vol. 62, No. 160 / Tuesday, August 19, 1997 /
Proposed Rules

[[Page 44096]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-CE-92-AD]
RIN 2120-AA64

Airworthiness Directives; Twin Commander Aircraft Corporation
500, 600, and 700 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 Twin Commander Aircraft Corporation 500, 600,
and 700 series airplanes. The proposed action would require installing
access holes in both wing leading edges and repetitively inspecting the
forward attach brackets and straps for cracks. Reports of cracks in the
wing to fuselage attachment brackets and straps, wing station (WS) 24,
and fuselage frames prompted the proposed action. The actions specified
by the proposed AD are intended to detect cracks at the wing to
fuselage attach points, which, if not detected and corrected, could
cause structural failure and loss of control of the airplane.

DATES: Comments must be received on or before October 24, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Central Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 95-CE-92-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 Twin Commander Aircraft Corporation, P.O. Box 3369, Arlington,
Washington, 98223; telephone (360) 435-9797; facsimile (360) 435-1112.
This information also may be examined at the Rules Docket at the
address above.

FOR FURTHER INFORMATION CONTACT: Jeffrey Morfitt, Aerospace Engineer,
FAA, Seattle Aircraft Certification Office, 1601 Lind Ave. 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 statement is made: ``Comments
to Docket No. 95-CE-92-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. 95-CE-92-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106.

Discussion

There have been 14 reports of cracking at the wing leading edge
spar and fuselage attach point in recent years on certain Twin
Commander 500, 600, and 700 series airplanes. Two Australian airplanes
out of the 14 were reported to have extensive cracking in the wing
leading edge spar, the wing station (W.S.) 24 rib, the fuselage station
(F.S.) 100 frame, and in the attachment brackets between the kick
fitting and the leading edge spar. Further investigation found 12 other
Twin Commander airplanes with similar cracking. In addition, Twin
Commander Models 690D and 695A airplanes were found to have adjacent
detail cracking while undergoing full scale fatigue tests. The Twin
Commander Models 690D and 695A airplanes are currently inspected in the
wing structure under Airworthiness Directive (AD) 95-12-23 which
mandates the procedures and actions in Twin Commander Service Bulletin
No. 213, dated July 24, 1994. This proposed action would cover
additional series airplanes as well as require repetitively inspecting
and modifying the wing leading edge by installing access holes for
thorough access to the fatigued areas.

Relevant Service Information

Twin Commander has issued Service Bulletin (SB) No. 223, dated
October 24, 1996 as amended by Revision Notice No. 1, dated May 8,
1997, which specifies installing access holes in both wing leading
edges, inspecting for cracks, and replacing or repairing any cracked
part and continuing to repetitively inspect.

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 detect cracks at the wing
to fuselage attach points, which, if not detected and corrected, could
cause structural failure and 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 Twin Commander 500, 600, and 700 series
airplanes of the same type design, the proposed AD would require the
following actions:

[[Page 44097]]

Note: Models 520 and 560 airplanes only are excluded from
installing the wing leading edge access holes and inspection
proposed in PART I of the above table.
Note: Models 690C and 695 airplanes are excluded from the
proposed inspection in PART III in the above table.

Cost Impact

The FAA estimates that 1,887 airplanes in the U.S. registry would
be affected by the proposed AD, that it would take approximately 82
workhours for PART I; 100 workhours for PART II (if required); and 7
workhours for PART III per airplane to accomplish the proposed action.
The average labor rate is approximately $60 an hour. Parts cost
approximately $410 for PART I and approximately $450 for PART II (if
required) per airplane. Based on these figures, the total cost impact
for PART I would be $5,330 per airplane, PART II (if required) would be
$6,450 per airplane, and PART III would be $420 per airplane. The U.S.
fleet cost is estimated to be $11,127,650, or $5,950 per airplane if no
damage is found; and $23,021,400 for the U.S. fleet, or $12,200 per
airplane if damage is found. For purposes of estimating the cost of the
proposed AD, the FAA is presuming that none of the owners/operators of
the affected airplanes have accomplished any of the actions on any of
the affected airplanes. In addition, the cost impact does not take into
consideration the costs of the repetitive inspections. The FAA has no
way of determining the number of repetitive inspections that may be
incurred over the life of the airplane.

Regulatory Flexibility Act Economic Analysis

Because the estimated cost for the proposed inspection and possible
repairs are expensive, the FAA conducted a Cost Analysis and Initial
Regulatory Flexibility Determination and Analysis for the proposed AD.
The Regulatory Flexibility Act of 1980 (RFA) was enacted by
Congress to assure that small entities are not unnecessarily and
disproportionately burdened by Government regulations. The RFA requires
agencies to review rules that may have a ``significant economic impact
on a substantial number of small entities,'' and, in cases where they
would, to conduct a Regulatory Flexibility Analysis in which
alternative actions are considered.
FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance,
defines ``significant economic impact'' as an annualized net compliance
cost, adjusted for inflation, which is greater than a threshold cost
level for defined entity types. A ``substantial number'' is defined as
a number that is at least eleven and that is more than one-third of the
small entities subject to a proposed rule, or any number of small
entities subject to a rule which is substantial in the judgment of the
rulemaking official. Small entities are defined as small businesses,
small not-for-profit organizations which are independently owned and
operated, or airports operated by small governmental jurisdictions.
With limited information available to airplane specific costs, a
range of per airplane costs can be estimated by constructing
hypothetical low- and high-cost scenarios. These scenarios are based on
three general presumptions: first, that these airplanes have
accumulated 6,000 hours TIS, and will be subject to the proposed AD
within the next 100 hours TIS; second, that all of these airplanes are
at the minimum and maximum extremes of annual TIS (200 or 300 hours),
remaining operating life (10 and 20 years), and the extent of cracking
(no cracking or cracking in the inspected areas); and third, that these
airplanes are of the model types incurring either the lowest or highest
costs.
The total low-cost scenario in 1997 dollars would be $5,570 ($4,805
discounted) per airplane over 10 years, with $5,330 of the costs
incurred in the first year. The annualized cost (again over 10 years)
would be $641 per airplane.
The total high-cost scenario in 1997 dollars would be $25,285 per
airplane ($16,487 discounted) over 30 years, with $15,865 of the costs
incurred in the first year. The annualized cost (again over 30 years)
would be $1,556.
The proposed AD would affect approximately 1,464 airplanes, of
which 366 are owned by individuals, 38 are owned by federal and state
agencies, and 847 are owned by 697 separate entities. Of the 697
entities, 1 entity owns 28 airplanes, 3 entities own between 10 and 12
airplanes, 19 separate entities own between 3 and 9 airplanes, thirty-
two entities own 2 airplanes, and 642 entities own 1 airplane. The FAA
cannot determine the size of all 697 owner entities, or the type of
business each entity is engaged in. The FAA also cannot conclusively
determine the costs of this AD. For illustration purposes, it was
calculated that the proposed AD would have hypothetical annualized
costs between $641 (the low-cost scenario) and $1,556 (the high-cost
scenario) per airplane. Due to the uncertainties involved with these
calculations, as well as with the ownership information, no
determinations can be made regarding ``significant economic impact on a
substantial number of small entities.''
The FAA has considered three alternatives to this proposed AD: (1)
take no federal action and rely on voluntary compliance with the Twin
Commander Service Bulletin No. 223. The FAA finds this alternative
unacceptable because of the consequences that could result; (2) mandate
inspecting fewer parts, and at longer intervals in the areas where the
wings attach to the fuselage. This

[[Page 44098]]

alternative is unacceptable because less stringent inspections could
fail to locate cracking in key parts of the airplane for too long a
period of time; (3) defer Federal action pending review of additional
data to determine whether to require the specified inspections. This
alternative is unacceptable because evidence already exists of cracking
in the wing and fuselage at the attach points which would be considered
structural failure.
Consequently, the FAA is unable to conclusively make an economic
impact evaluation based on information available.

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,
could have a significant economic impact, positive or negative, on a
substantial number of small entities under the criteria of the
Regulatory Flexibility Act (a determination was not able to be made). 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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

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

Twin Commander Aircraft Corporation: Docket No. 95-CE-92-AD.

Applicability: Models 500, 500A, 500B, 500S, 500U, 520, 560,
560A, 560E, 560F, 680, 680E, 680F, 680FL, 680FLP, 680FP, 680T, 680V,
680W, 681, 685, 690, 690A, 690B, 690C, 690D, 695, 695A, 695B and 720
airplanes (all serial numbers), certificated in any category.

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 (f) 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 cracks at the wing to fuselage attach points, which,
if not detected and corrected, could cause structural failure and
loss of control of the airplane, accomplish the following:
(a) For all models except Models 520, 560, 690C and 695,
accomplish the actions in the following table in accordance with the
Compliance section and PART I, II, and III of the ACCOMPLISHMENT
INSTRUCTIONS sections of Twin Commander Aircraft Corporation (Twin
Commander) Service Bulletin (SB) No. 223, dated October 24, 1996 as
amended by Revision Notice No. 1, dated May 8, 1997:

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A B C
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PART I............................... Upon the accumulation If cracked, prior to If no cracks are found,
of 6,000 hours total further flight, repeat inspection at
time-in-service (TIS) replace the brackets 1,000 hour (hr.)
or within the next 100 and straps or repair intervals until cracks
hours TIS, whichever the part by an are found, replace the
occurs later, install approved repair scheme cracked part or repair
access holes in left (see paragraph (b) of by an approved repair
and right wing leading this AD). Then, scheme (see paragraph
edges and inspect the accomplish PART II of (b) of this AD), then
forward attach this AD. accomplish PART II.
brackets and straps
for cracks.
(Accomplish in (Accomplish in (Accomplish in
accordance with PART I accordance with PART I accordance with PART I
of Compliance Section of Compliance Section of Compliance Section
in Twin Commander SB in Twin Commander SB in Twin Commander SB
223, dated Oct. 24, 223, dated Oct. 24, 223, dated Oct. 24,
1996 as amended by 1996 as amended by 1996 as amended by
Revision Notice No. 1, Revision Notice No. 1, Revision Notice No. 1,
dated May 8, 1997.) dated May 8, 1997.) dated May 8, 1997.)
PART II.............................. Inspect for cracks at If cracked, prior to After repair or
the wing leading edge further flight, replacement is
close-outs, upper & replace any cracked accomplished, continue
lower return flange part or repair the to inspect at 6,000
radius, fuselage frame part with an approved hr. intervals.
where tee bracket repair scheme (see
attaches, inboard side paragraph (b) of this
of attach bracket and AD). If no cracks are
frame tee bracket. found, continue to
repetitively inspect
at 1,000 hour TIS
intervals.
(Accomplish in (Accomplish in (Accomplish in
accordance with PART accordance with PART accordance with PART
II of Compliance II of Compliance II of Compliance
Section in Twin Section in Twin Section in Twin
Commander SB 223, Commander SB 223, Commander SB 223,
dated Oct. 24, 1996 as dated Oct. 24, 1996 as dated Oct. 24, 1996 as
amended by Revision amended by Revision amended by Revision
Notice No. 1, dated Notice No. 1, dated Notice No. 1, dated
May 8, 1997.) May 8, 1997.) May 8, 1997.)

[[Page 44099]]

For pressurized If cracked, prior to If no cracks, repeat
airplanes, at 6,000 further flight, repair inspection at 1,000
hr. total TIS or with an approved hr. intervals until
within the next 100 repair scheme (see cracks are found, then
hours TIS whichever paragraph (b) of this accomplish PART III B
occurs later, inspect AD), and continue to of this AD
fuselage station inspect at 1,000 hr.
(F.S.) 100 for cracks. intervals.
PART III............................. For non-pressurized (Accomplish in (Accomplish in
airplanes, at 12,000 accordance with PART accordance with PART
hr. total TIS or III of Compliance III of Compliance
within the next 100 Section in Twin Section in Twin
hours TIS whichever Commander SB 223, Commander SB 223,
occurs later, inspect dated Oct. 24, 1996 as dated Oct. 24, 1996 as
F.S. 100 for cracks.. amended by Revision amended by Revision
(Accomplish in Notice No. 1, dated Notice No. 1, dated
accordance with PART May 8, 1997.) May 8, 1997.)
III of Compliance
Section in Twin
Commander SB 223,
dated Oct. 24, 1996 as
amended by Revision
Notice No. 1, dated
May 8, 1997.)
----------------------------------------------------------------------------------------------------------------

(b) Obtain an FAA-approved repair scheme from the manufacturer
through the Manager of the Seattle Aircraft Certification Office at
the address specified in paragraph (f) of this AD.
(c) For Twin Commander Models 520 and 560 airplanes, upon the
accumulation of 6,000 hours total TIS or within the next 100 hours
TIS whichever occurs later, accomplish PART II of the table in
paragraph (a) of this AD. Accomplish PART III in accordance with the
compliance times in the above table of paragraph (a). These models
are excluded from the wing leading edge access hole installation in
PART I of the table in paragraph (a) of this AD.
(d) For Twin Commander Models 690C and 695 airplanes, accomplish
PARTS I and II in accordance with the compliance times in the above
table of paragraph (a). These Models are excluded from PART III of
the table in paragraph (a) of this AD.
(e) 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.
(f) An alternative method of compliance or adjustment of the
initial or repetitive compliance times that provides an equivalent
level of safety may be approved by the Manager, Seattle Aircraft
Certification Office, 1601 Lind Ave. 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 Aircraft Certification Office.

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

(g) All persons affected by this directive may obtain copies of
the document referred to herein upon request to Twin Commander
Aircraft Corporation, P.O. Box 3369, Arlington, Washington 98223;
telephone (360) 435-9797; facsimile (360) 435-1112; 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 August 12, 1997.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 97-21873 Filed 8-18-97; 8:45 am]
BILLING CODE 4910-13-P