Airworthiness Directives; Pilatus Aircraft Ltd. Models PC-6, PC- 6/A, PC-6/B, and PC-6/C Series Airplanes

[Federal Register Volume 63, Number 107 (Thursday, June 4, 1998)]
[Rules and Regulations]
[Pages 30370-30372]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-14607]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-09-AD; Amendment 39-10558; AD 98-12-01]
RIN 2120-AA64


Airworthiness Directives; Pilatus Aircraft Ltd. Models PC-6, PC-
6/A, PC-6/B, and PC-6/C Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies to certain Pilatus Aircraft Ltd. (Pilatus) Models PC-6, PC-6/A, 
PC-6/B, and PC-6/C series airplanes equipped with turbo-prop engines. 
This AD requires modifying the fuel system to improve the venting 
between the collector tank, the main wing tanks, and the engine. This 
AD is the result of mandatory continuing airworthiness information 
(MCAI) issued by the airworthiness authority for Switzerland. The 
actions specified by this AD are intended to prevent engine fuel 
starvation during maximum climb and descent caused by poor fuel tank 
venting with low fuel levels, which could result in a loss of engine 
power during critical phases of flight.

DATES: Effective July 13, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 13, 1998.

ADDRESSES: Service information that applies to this AD may be obtained 
from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6370 Stans, 
Switzerland; telephone: +41 41-6196 233; facsimile: +41 41-6103 351. 
This information may also be examined at the Federal

[[Page 30371]]

Aviation Administration (FAA), Central Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 97-CE-09-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106; or at the Office of the 
Federal Register, 800 North Capitol Street, NW, suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Mr. Roman T. Gabrys, Aerospace 
Engineer, FAA, Small Airplane Directorate, Airplane Certification 
Service, 1201 Walnut, suite 900, Kansas City, Missouri 64106; 
telephone: (816) 426-6934; facsimile: (816) 426-2169.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to include an AD that would apply to certain Pilatus PC-6, 
PC-6/A, PC-6/B, and PC-6/C series airplanes was published in the 
Federal Register as a notice of proposed rulemaking (NPRM) on March 25, 
1998 (63 FR 14385). The NPRM proposed to require modifying the 
airplane's fuel venting system. Accomplishment of the proposed action 
as specified in the NPRM would be in accordance with Pilatus PC-6 
Service Bulletin No. PC-6-SB-171, dated October 18, 1995.
    The NPRM was the result of mandatory continuing airworthiness 
information (MCAI) issued by the airworthiness authority for 
Switzerland.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
minor editorial corrections. The FAA has determined that these minor 
corrections will not change the meaning of the AD and will not add any 
additional burden upon the public than was already proposed.

Differences Between the Service Information, the Federal Office for 
Civil Aviation (FOCA) AD, and This AD Action

    The manufacturer recommends the modification of the fuel venting 
system and the insertion of a temporary revision to the AFM, and FOCA 
of Switzerland requires the temporary AFM insertion and the 
modification of the fuel venting system for airplanes operated in 
Switzerland. The FOCA of Switzerland requires the AFM revision be 
accomplished prior to further flight and requires the revision to 
remain in the AFM until the venting modification is accomplished. The 
FOCA of Switzerland additionally requires that the modification be 
accomplished within 90 days from receipt of the service bulletin.
    The FAA will not require insertion of the temporary AFM revision; 
however, the FAA will require the modification of the fuel venting 
system at the calendar compliance time that is required by the FOCA of 
Switzerland.

Cost Impact

    The FAA estimates that 29 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 10 workhours per 
airplane to accomplish this action, and that the average labor rate is 
approximately $60 an hour. Parts cost approximately $614 per airplane. 
Based on these figures, the total cost impact of this AD on U.S. 
operators is estimated to be $35,206, or $1,214 per airplane.

Compliance Time of This AD

    Since the airplane's poor fuel tank venting causes engine fuel 
starvation during flights at maximum climb and decent, this unsafe 
condition is not a result of the number of times the airplane is 
operated. The chance of this situation occurring is the same for an 
airplane with 10 hours time-in-service (TIS) as it would be for an 
airplane with 500 hours TIS. For this reason, the FAA has determined 
that a compliance based on calendar time should be utilized in this AD 
in order to assure that the unsafe condition is addressed on all 
airplanes in a reasonable time period.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does 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) 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 final evaluation prepared for this 
action is contained 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

98-12-01  Pilatus Aircraft Ltd: Amendment 39-10558; Docket No. 97-
CE-09-AD.

    Applicability: Models PC-6, PC-6-H1, PC-6-H2, PC-6/350, PC-6/
350-H1, PC-6/350-H2, PC-6/A, PC-6/A-H1, PC-6/A-H2, PC-6/B-H2, PC-6/
B1-H2, PC-6/B2-H2, PC-6/B2-H4, PC-6/C-H2, and PC-6/C1-H2 airplanes, 
serial numbers 001 through 915, certificated in any category, that 
are equipped with turbo-prop engines.

    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 (c) 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 3 calendar months after the 
effective date of this AD, unless already accomplished.
    To prevent engine fuel starvation during maximum climb and 
descent caused by poor fuel tank venting with low fuel levels, which 
could result in a loss of engine power during critical phases of 
flight, accomplish the following:
    (a) Modify the fuel venting system in accordance with the 
Accomplishment

[[Page 30372]]

Instructions section in Pilatus PC-6 Service Bulletin No. PC-6-SB-
171, dated October 18, 1995.
    (b) Special flight permits may be issued in accordance with 
sections 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.
    (c) 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, 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Small Airplane Directorate.

    (d) Questions or technical information related to Pilatus 
Service Bulletin No. PC-6-SB-171, dated October 18, 1995, should be 
directed to Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6370 
Stans, Switzerland; telephone: +41 41-6196 233; facsimile: +41 41-
6103 351. 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.
    (e) The modification required by this AD shall be done in 
accordance with Pilatus Service Bulletin No. PC-6-SB-171, dated 
October 18, 1995. This incorporation by reference was approved by 
the Director of the Federal Register in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51. Copies may be obtained from Pilatus 
Aircraft Ltd., Customer Liaison Manager, CH-6370 Stans, Switzerland. 
Copies may be inspected at the FAA, Central Region, Office of the 
Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri, or at the Office of the Federal Register, 800 North 
Capitol Street, NW, suite 700, Washington, DC.

    Note 3: The subject of this AD is addressed in Swiss AD HB 95-
451, dated November 1, 1995.

    (f) This amendment becomes effective on July 13, 1998.

    Issued in Kansas City, Missouri, on May 22, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-14607 Filed 6-3-98; 8:45 am]
BILLING CODE 4910-13-U

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