[Federal Register Volume 64, Number 113 (Monday, June 14, 1999)]
[Proposed Rules]
[Pages 31758-31760]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14936]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-CE-10-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 modifying 
the generator 2 excitation by removing certain diodes and installing a 
new 5-amp circuit breaker and suppression filter. 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 damage to 
electrical components if the generator 2 is not switched off prior to 
engine shutdown and it overheats, which could result in loss of 
electrical power to certain critical airplane components.

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-10-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, 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

[[Page 31759]]

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-10-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-10-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 two instances of the 
generator 2 not coming on-line during a normal start-up procedure. When 
re-attempting to start-up the generator 2, smoke was noticed in the 
area of the flight compartment floor.
    The generator 2 control unit is not designed to prevent electrical 
feedback from the generator 2 field excitation on engine shut-down. If 
the pilot does not switch off the generator 2 prior to engine shutdown, 
voltage spikes are created at relay K234. Consequent overheating and 
damage to electrical components of the generator control circuit could 
then occur.
    This condition could exist on airplanes with one of the following 
generators installed:

--a BOSCH Generator 2, part number (P/N) 524.32.12.158. This generator 
is installed at the factory on Pilatus Models PC-12 and PC-12/45 
airplanes beginning with manufacturer serial number 231 and could be 
installed on airplanes with a manufacturer serial number in the range 
of 101 through 230 by incorporating Pilatus Service Bulletin No. 24-
010, dated September 28, 1998; or
--an ELECTRO SYSTEMS Generator 2, P/N 978.87.24.121, with Pilatus 
Service Bulletin No. 24-009 (installation of support bracket and cut-
out relay) incorporated. This generator is installed at the factory on 
Pilatus Models PC-12 and PC-12/45 airplanes with a manufacturer serial 
number in the range of 101 through 230. AD 99-06-17, Amendment 39-11081 
(64 FR 13882, March 23, 1999), requires installing the support bracket 
and cut-out relay specified in Pilatus Service Bulletin No. 24-009, 
dated September 23, 1998, on Pilatus Models PC-12 and PC-12/45 
airplanes with a manufacturer serial number in the range of 101 through 
180. This service bulletin is incorporated at the factory on airplanes 
with a manufacturer serial number in the range of 181 through 230.

    This condition, if not corrected, could result in the generator 2 
not going on-line with consequent loss of electrical power to certain 
critical airplane components.

Relevant Service Information

    Pilatus has issued Service Bulletin No. 24-012, dated February 19, 
1999, which specifies procedures for modifying the generator 2 
excitation by removing certain diodes and installing a new 5-amp 
circuit breaker and suppression filter.
    The FOCA of Switzerland classified this service bulletin as 
mandatory and issued Swiss AD HB 99-143, dated February 19, 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 modifying the generator 2 
excitation by removing certain diodes and installing a new 5-amp 
circuit breaker and suppression filter.
    Accomplishment of the proposed action would be required in 
accordance with Pilatus Service Bulletin No. 24-012, dated February 19, 
1999.

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 5 
workhours per airplane to accomplish the proposed action, and that the 
average labor rate is approximately $60 an hour. Parts will be provided 
at no cost to the owners/operators of the affected aircraft. Based on 
these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $20,700, or $300 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 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.

[[Page 31760]]

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-10-AD. Applicability: Models 
PC-12 and PC-12/45 airplanes, manufacturer serial numbers 101 
through MSN 260, 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 damage to electrical components if the generator 2 is 
not switched off prior to engine shutdown and it overheats, which 
could result in loss of electrical power to certain critical 
airplane components, accomplish the following:
    (a) Within the next 100 hours time-in-service (TIS) after the 
effective date of this AD, modify the generator 2 excitation by 
removing certain diodes and installing a new 5-amp circuit breaker 
and suppression filter. Perform these actions in accordance with the 
ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 
24-012, dated February 19, 1999.

    Note 2: The affected airplanes incorporate one of the following 
generators:

--a BOSCH Generator 2, part number (P/N) 524.32.12.158. This 
generator is installed at the factory on Pilatus Models PC-12 and 
PC-12/45 airplanes beginning with manufacturer serial number 231 and 
could be installed on airplanes with a manufacturer serial number in 
the range of 101 through 230 by incorporating Pilatus Service 
Bulletin No. 24-010, dated September 28, 1998; or
--an ELECTRO SYSTEMS Generator 2, P/N 978.87.24.121, with Pilatus 
Service Bulletin No. 24-009 (installation of support bracket and 
cut-out relay) incorporated. This generator is installed at the 
factory on Pilatus Models PC-12 and PC-12/45 airplanes with a 
manufacturer serial number in the range of 101 through 230. AD 99-
06-17, Amendment 39-11081 (64 FR 13882, March 23, 1999), requires 
installing the support bracket and cut-out relay specified in 
Pilatus Service Bulletin No. 24-009, dated September 23, 1998, on 
Pilatus Models PC-12 and PC-12/45 airplanes with a manufacturer 
serial number in the range of 101 through 180. This service bulletin 
is incorporated at the factory on airplanes with a manufacturer 
serial number in the range of 181 through 230.

    (b) As of the effective date of this AD, no person may install, 
on any affected airplane, a generator 2 that does not have the 
modification referenced in paragraph (a) of this AD incorporated.
    (c) Special flight permits may be issued in accordance with 
Secs. 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. 24-012, dated February 19, 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-
143, dated February 19, 1999.

    Issued in Kansas City, Missouri, on June 4, 1999.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-14936 Filed 6-11-99; 8:45 am]
BILLING CODE 4910-13-U