[Federal Register Volume 64, Number 113 (Monday, June 14, 1999)]
[Proposed Rules]
[Pages 31756-31758]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14937]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-CE-20-AD]
RIN 2120-AA64


Airworthiness Directives; Pilatus Aircraft Ltd. Models PC-12 and 
PC-12/45 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 certain Pilatus Aircraft Ltd. (Pilatus) Models 
PC-12 and PC-12/45 airplanes. The proposed AD would require replacing 
all flap drive shafts with flap drive shafts of improved design, 
installing additional gaskets on the power drive unit, and modifying 
the attachment and supporting hardware. The proposed AD is the result 
of mandatory continuing airworthiness information (MCAI) issued by the 
airworthiness authority for Switzerland. The actions specified by the 
proposed AD are intended to prevent the flap drive shafts from 
corroding to the point where the flexible shafts in the flap drive 
system rupture, which could result in the inability to utilize the flap 
system with reduced airplane control.

DATES: Comments must be received on or before July 14, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 99-CE-20-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., Customer Liaison Manager, CH-6371 Stans, 
Switzerland; telephone: +41 41 619 63 19; facsimile: +41 41 610 33 51. 
This information also may be examined at the Rules Docket at the 
address above.

FOR FURTHER INFORMATION CONTACT: Mr. Roman T. Gabrys, Aerospace 
Engineer,

[[Page 31757]]

FAA, Small Airplane Directorate, 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. 99-CE-20-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 Regional Counsel, Attention: 
Rules Docket No. 99-CE-20-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 Models PC-12 and PC-
12/45 airplanes. The FOCA of Switzerland reports several incidents of 
corroded inner drive cables of the flap flexible drive shafts.
    Investigation of these incidents shows that moisture from the 
pressurized cabin can enter the flap drive shafts through the unsealed 
areas of the flap drive shaft attachments and the shaft casings. Over 
time, this moisture leads to corroded flap drive shafts.
    This condition, if not corrected in a timely manner, could result 
in the flexible shafts in the flap drive system rupturing with possible 
reduced airplane control if the pilot lost the ability to utilize the 
flap system.

Relevant Service Information

    Pilatus has issued Service Bulletin No. 27-003, dated March 8, 
1999, which specifies procedures for replacing all flap drive shafts 
with flap drive shafts of improved design, installing additional 
gaskets on the power drive unit, and modifying the attachment and 
supporting hardware.
    The FOCA of Switzerland classified this service bulletin as 
mandatory and issued Swiss AD HB 99-241, dated May 8, 1999, in order to 
assure the continued airworthiness of these airplanes in Switzerland.

The FAA's Determination

    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. Pursuant to this 
bilateral airworthiness agreement, the FOCA of Switzerland has kept the 
FAA informed of the situation described above.
    The FAA has examined the findings of the FOCA of Switzerland; 
reviewed all available information, including the service information 
referenced above; and determined that AD action is necessary for 
products of this type design that are certificated for operation in the 
United States.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Pilatus PC-12 and PC-12/45 airplanes of the 
same type design registered in the United States, the FAA is proposing 
AD action. The proposed AD would require replacing all flap drive 
shafts with flap drive shafts of improved design, installing additional 
gaskets on the power drive unit, and modifying the attachment and 
supporting hardware.
    Accomplishment of the proposed action would be required in 
accordance with Pilatus Service Bulletin No. 27-003, dated March 8, 
1999.

Compliance Time of the Proposed AD

    The unsafe condition specified by the proposed AD is caused by 
corrosion. Corrosion can occur regardless of whether the aircraft is 
being operated. For example, corrosion could develop on one of the 
affected airplanes at a certain time; then, if allowed to go 
undetected, the corrosion could develop into a more serious problem 
even if the airplane is in storage. Therefore, to assure that the 
unsafe condition specified in the proposed AD does not go undetected 
for a long period of time, the compliance is presented in calendar time 
instead of hours time-in-service (TIS).

Cost Impact

    The FAA estimates that 69 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 19 
workhours per airplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Parts will be provided 
to the owners/operators of the affected aircraft free-of-charge. Based 
on these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $78,660, or $1,140 per airplane.

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

[[Page 31758]]

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. 99-CE-20-AD.

    Applicability: Models PC-12 and PC-12/45 airplanes, manufacturer 
serial number (MSN) 101 through MSN 239, 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 (d) 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 the flap drive shafts from corroding to the point 
where the flexible shafts in the flap drive system rupture, which 
could result in the inability to utilize the flap system with 
reduced airplane control, accomplish the following:
    (a) Within the next 4 calendar months after the effective date 
of this AD, accomplish the following in accordance with the 
Accomplishment Instructions section of Pilatus Service Bulletin No. 
27-003, dated March 8, 1999:
    (1) Replace all flap drive shafts with flap drive shafts of 
improved design (part numbers as specified in paragraphs (b)(1) and 
(b)(2) of this AD);
    (2) Install additional gaskets on the power drive unit; and
    (3) Modify the attachment and supporting hardware.
    (b) As of the effective date of this AD, no person may install, 
on any affected airplane, a flap drive shaft assembly that is not of 
the following part numbers (or FAA-approved equivalent part 
numbers):
    (1) Part number 945.02.02.201: Flap Drive Shaft 953D100-5 
(Inboard); and
    (2) Part-number 945.02.02.202: Flap Drive Shaft 953D100-7 
(Outboard).

    Note 2: The FAA recommends that the owner/operator of the 
affected airplanes insert Pilatus Temporary Revision No.27-07, dated 
January 8, 1999, into the PC12 Maintenance Manual at the same time 
this AD is accomplished to assure that the maintenance procedures 
for the improved design parts are current.

    (c) Special flight permits may be issued in accordance with 
Sec. Sec. 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.
    (d) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be 
approved by the Manager, Small Airplane Directorate, 1201 Walnut, 
suite 900, Kansas City, Missouri 64106. 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.

    (e) Questions or technical information related to Pilatus 
Service Bulletin No: 27-003, dated March 8, 1999, should be directed 
to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, 
Switzerland; telephone: +41 41 619 63 19; facsimile: +41 41 610 33 
51. This service information may be examined at the FAA, Central 
Region, Office of the Regional Counsel, Room 1558, 601 E. 12th 
Street, Kansas City, Missouri 64106.

    Note 4: The subject of this AD is addressed in Swiss AD HB 99-
241, dated May 8, 1999.

    Issued in Kansas City, Missouri, on June 4, 1999.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-14937 Filed 6-11-99; 8:45 am]
BILLING CODE 4910-13-U