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[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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[[Page 29501]]

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
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