[Federal Register Volume 61, Number 113 (Tuesday, June 11, 1996)]
[Proposed Rules]
[Pages 29500-29502]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-14694]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-CE-85-AD]
RIN 2120-AA64
Airworthiness Directives: Pilatus Aircraft Ltd., Model PC-6
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 Pilatus Aircraft Ltd. (Pilatus) Model PC-6
airplanes. The proposed action would require inspecting for loose or
sheared rivets in the hinge brackets on the horizontal stabilizer and
inspecting for incorrect spacing tolerance of the hinge brackets. If
the rivets are found loose or sheared, the proposed AD would require
replacing the rivets and also re-positioning the hinge brackets, if
found incorrectly spaced. Several reports of rivets shearing on the
hinge brackets prompted the proposed action. The actions specified in
this proposed AD are intended to prevent structural failure of the
hinge bracket on the horizontal stabilizer, which could result in
partial or complete loss of control of the horizontal stabilizer and
loss of control of the airplane.
DATES: Comments must be received on or before August 14, 1996.
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-85-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 Pilatus Aircraft Ltd., CH-6370 Stans, Switzerland. This
information also may be examined at the Rules Docket at the address
above.
FOR FURTHER INFORMATION CONTACT: Mr. Roman T. Gabrys, Project Officer,
Small Airplane Directorate, Aircraft Certification Service, FAA, 1201
Walnut, suite 900, Kansas City, Missouri 64106; telephone (816) 426-
6932; facsimile (816) 426-2169.
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-85-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-85-AD, Room 1558, 601 E. 12th Street,
Kansas City, Missouri 64106.
Discussion
The Federal Office for Civil Aviation (FOCA), which is the
airworthiness authority for Switzerland, recently notified the FAA that
an unsafe condition may exist on certain Pilatus Model PC-6 airplanes.
The FOCA has received several reports of sheared or loose rivets in the
hinge bracket that attaches the horizontal stabilizer to the fuselage.
Investigation reveals that pre-loads in the hinge bracket flanges may
exist due to tightness of the fit of the spacer, or in certain
instances, the hinge bracket is not positioned or spaced correctly.
This condition can substantially affect the load carrying capability of
these brackets, thus causing the rivets to shear or loosen, which could
lead to structural failure of the horizontal stabilizer.
Pilatus Aircraft Ltd. has issued service bulletin (SB) PC-6 165,
dated February 7, 1994, which specifies procedures for inspecting for
sheared or loose rivets, replacing any sheared or loose rivets with new
rivets, and checking the spacing tolerance of the hinge brackets.
FOCA classified this service bulletin as mandatory and has issued
airworthiness directive (AD) HB 94-086, dated June 4, 1994, in order to
ensure the continued airworthiness of these airplanes in Switzerland.
This airplane model is manufactured in Switzerland and is type
certificated for operation in the United States under the provisions of
Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the
applicable bilateral airworthiness agreement between Switzerland and
the United States. Pursuant to this bilateral airworthiness agreement,
the Switzerland FOCA has kept the FAA informed of the situation
described above. The FAA has examined the findings of the Switzerland
FOCA, reviewed all available information, and determined that AD action
is necessary for products of this type design that are certificated for
operation in the United States.
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 a reduction in the
structural integrity of the hinge bracket and tailplane, which could
result in partial or complete loss of control of the horizontal
stabilizer and loss of control of the airplane.
Since an unsafe condition has been identified that is likely to
exist or develop in other Pilatus Model PC-6 airplanes of the same type
design registered in the United States, the proposed AD would require
the following:
--Inspecting the hinge brackets attached to the fuselage for loose or
sheared rivets,
--Inspecting the hinge brackets for correct spacing tolerance and
positioning,
--Removing the brackets and adjusting any incorrect spacing or
positioning, and
--Replacing any loose or sheared rivets with new rivets.
The FAA estimates that one airplane in the U.S. registry would be
affected by the proposed AD, that it would take less than 1 workhour
per airplane to accomplish the proposed actions, and that the average
labor rate is approximately $60 an hour. Based on these figures, the
total cost impact of the proposed AD for the only U.S. operator is
estimated to be $60. This is the cost of the inspection only and does
not include the cost for replacing any loose rivets, if found. This
figure is based on the assumption that the affected owner/
[[Page 29502]]
operator of the affected airplane has not performed the inspection or
modification.
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. 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:
Pilatus Aircraft Ltd.: Docket No. 95-CE-85-AD.
Applicability: Model PC-6 Airplanes (serial numbers 825 through
892).
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 (e) 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 within the next 75 hours time-in-service
(TIS), after the effective date of this AD, unless already
accomplished.
Note 2: The compliance time required in this AD takes precedence
over the compliance time in Pilatus Service Bulletin PC-6 165, dated
February 7, 1994.
To prevent structural failure of the hinge bracket on the
horizontal stabilizer, which could result in partial or complete
loss of control of the horizontal stabilizer and loss of control of
the airplane, accomplish the following:
(a) Inspect the hinge brackets on the horizontal stabilizer for
sheared or loose rivets in accordance with paragraph 2.A. in the
ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin (SB)
PC-6 165, dated February 7, 1994.
(b) Inspect the spacing tolerance of the hinge bracket in
accordance with paragraph 2.C. in the ACCOMPLISHMENT INSTRUCTIONS
section of Pilatus SB PC-6 165, dated February 7, 1994.
(c) If there are loose or sheared rivets or if the bracket
spacing is out of the spacing tolerance, prior to further flight,
modify the position and space tolerance of the hinge brackets and
replace any loose or sheared rivets in accordance with paragraph
2.D. in the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus SB PC-6
165, dated February 7, 1994.
(d) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviations Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an equivalent level of safety may be
approved by the Manager, Small Airplane Directorate. The request
shall be forwarded through an appropriate FAA Maintenance Inspector,
who may add comments and then send it to the Manager, Small Airplane
Directorate.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Small Airplane Directorate.
(f) All persons affected by this directive may obtain copies of
the document referred to herein upon request to Pilatus Aircraft
Ltd., CH-6370 Stans, Switzerland; 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.
Issued in Kansas City, Missouri on June 4, 1996.
Henry A. Armstrong,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-14694 Filed 6-10-96; 8:45 am]
BILLING CODE 4910-13-U
