[Federal Register Volume 62, Number 33 (Wednesday, February 19, 1997)]
[Proposed Rules]
[Pages 7377-7378]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-3958]
[[Page 7377]]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-CE-47-AD]
RIN 2120-AA64
Airworthiness Directives; Air Tractor Incorporated Models AT-301,
AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to supersede AD 95-20-06, which
currently requires inspecting the front spar attachment lugs and the
rear spar for fatigue cracks and modifying the vertical fin if cracks
are found. If no cracks are found, continue repetitively inspecting the
area until cracks are found; and then incorporate the modification as a
terminating action. The proposed action would retain the actions
required in AD 95-20-06 for all Air Tractor models that have a \3/16\-
inch fin front spar fitting. Air Tractor models that are fitted with a
\1/4\-inch fin front spar fitting would not be required to accomplish
this action. This action is prompted by two incident reports involving
the failure of the front and rear spar attachment of the vertical fin.
The actions specified by this AD are intended to prevent in-flight
vertical fin structural failure of the front spar attachments and
eventually the rear spar attachment, which, if not detected and
corrected, could result in loss of directional control and loss of
control of the airplane.
DATES: Comments must be received on or before April 21, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Central Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 96-CE-47-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 Air Tractor Incorporated, P. O. Box 485, Olney, Texas 76374. This
information also may be examined at the Rules Docket at the address
above.
FOR FURTHER INFORMATION CONTACT: Bob May, Aerospace Engineer, FAA,
Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth,
Texas 76193-0150; telephone (817) 222-5156; facsimile (817) 222-5960.
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. 96-CE-47-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. 96-CE-47-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106.
Discussion
It has been brought to the attention of the FAA that AD 95-20-06,
which is applicable to Air Tractor Models AT-301, AT-302, AT-400, AT-
400A, AT-401, AT-402, AT-501, and AT-502 airplanes, should not have
included models that are fitted with \1/4\-inch thick fin front spar
attach fittings. The current AD requires inspecting for cracks on all
of the models referenced above, regardless of whether they have \1/4\-
inch or \3/16\-inch thick front spar attachment fitting, and if no
cracks are found, repetitively inspecting at different time intervals.
The time interval would depend on the thickness of the fin front spar
attach fitting on the airplane. If cracks are found, the current AD
requires modifying the front spar attachment. Since publication of AD
95-20-06, further investigation has revealed that the only Air Tractor
models developing cracks are the models fitted with a \3/16\-inch thick
front spar attachment fitting. For this reason, the FAA is proposing to
supersede the current AD to change the instructions of the AD.
Relevant Service Information
Air Tractor has issued a revised Service Letter (SL) No. 138,
Revised August 7, 1996, which specifies procedures for inspecting,
repetitively inspecting, and modifying the Air Tractor Models that have
the 3/16-inch thick front spar attach fitting.
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 in-flight vertical
fin structural failure of the front spar attachments and eventually the
rear spar attachment, which, if not detected and corrected, could
result in loss of directional control 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 Air Tractor Incorporated Models AT-301, AT-
302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 airplanes of
the same type design that are fitted with 3/16-inch thick front spar
attachment fittings, the proposed AD would supersede AD 95-20-06 with a
new AD that would require inspecting the fin front spar attach fitting
lugs of models that have 3/16-inch thick fin front spar attach fittings
for cracks and if cracks are found, prior to further flight, modifying
the front spar attachment lugs. If no cracks are found, the proposed AD
would require repetitively inspecting the front spar attachment lugs
until cracks are found. Accomplishing the modification would terminate
the repetitive inspections.
Cost Impact
The FAA estimates that 24 airplanes in the U.S. registry would be
affected by the proposed AD, that it would take approximately 16
workhours per airplane to accomplish the proposed action, and that the
average labor rate is approximately $60 an hour. Parts cost
approximately $10 per airplane. Based on these figures, the total cost
impact of the proposed AD on U.S. operators is estimated to be $970 per
airplane and
[[Page 7378]]
$23,280 for the U.S. fleet. The FAA has no way of determining how many
owners/operators of these affected airplanes have accomplished 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 USC 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing Airworthiness Directive
(AD) 95-20-06, Amendment 39-9384, and by adding a new AD to read as
follows:
Air Tractor Incorporated: Docket No. 96-CE-47-'AD; Supersedes AD 95-
20-06, Amendment 39-9384.
Applicability: The following airplane models and serial numbers
that have not accomplished the modification in Snow Engineering Company
Report No. 138, dated July 29, 1995, which is referenced in superseded
AD 95-20-06, certificated in any category:
Note 1: The modification in Snow Engineering Company Report No.
138, dated July 29, 1995 and AD 95-20-06 required the airplanes to
replace 3/16-inch thick fin front spar attach fittings with 1/4-inch
thick fin front spar attach fittings.
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Models Serial Nos.
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AT-301 and AT-401................... 301-0261 through 301-0736, and 401-
0662 through 401-0736 that have
been converted to turbine
powerplants and equipped with the
all metal rudder, part number (P/
N) 30456-1.
AT-302.............................. All aircraft equipped with the all
metal rudder, P/N 30456-1.
AT-400 and AT-400A.................. All aircraft equipped with the all
metal rudder, P/N 30456-1.
AT-402.............................. 402-0694 and 402-0695 through 402-
0736.
AT-501.............................. 501-0002 through 501-0030 that
have been converted to turbine
powerplants and equipped with the
all metal rudder, P/N 30456-1.
AT-502.............................. 502-0002 through 502-0030.
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Note 2: 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 initially within the next 25 hours time-in-
service (TIS) after the effective date of this AD, unless already
accomplished, and thereafter as indicated in the body of this AD.
To prevent in-flight vertical fin structural failure of the
front spar attachments and eventually the rear spar attachment,
which, if not detected and corrected, could result in loss of
directional control and loss of control of the airplane, accomplish
the following:
(a) Inspect the fin front spar attachment fittings for fatigue
cracks in accordance with the INSTRUCTIONS section of the Snow
Engineering Report (SER) number (No.) 138, Revised August 7, 1996.
(b) If no cracks are found during the initial inspection, repeat
the inspection required by paragraph (a) of this AD at intervals not
to exceed 25 hours TIS thereafter in accordance with the
INSTRUCTIONS section of the SER No. 138, Revised August 7, 1996.
(c) If cracks are found during any inspections required by this
AD, prior to further flight, modify the fin front spar attachment
fittings in accordance with the INSTRUCTIONS section of the SER No.
138, Revised August 7, 1996.
(d) Incorporating the modification specified in paragraph (c) of
this AD is considered terminating action for the repetitive
inspection requirements of this AD.
(e) 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.
(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, Fort Worth Airplane
Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas
76193-0150. The request shall be forwarded through an appropriate
FAA Maintenance Inspector, who may add comments and then send it to
the Manager, Fort Worth Airplane Certification Office. Alternative
methods of compliance approved in accordance with AD 95-20-06 are
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 Fort Worth Aircraft Certification Office.
(g) All persons affected by this directive may obtain copies of
the document referred to herein upon request to Air Tractor
Incorporated, P. O. Box 485, Olney, Texas 76374; 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.
(h) This amendment supersedes AD 95-20-06, Amendment 39-9384.
Issued in Kansas City, Missouri, on February 10, 1997.
Henry A. Armstrong,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-3958 Filed 2-18-97; 8:45 am]
BILLING CODE 4910-13-U
