[Federal Register Volume 68, Number 65 (Friday, April 4, 2003)]
[Proposed Rules]
[Pages 16458-16460]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-8199]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-CE-12-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 all Pilatus Aircraft Ltd. (Pilatus) Model PC-6 
airplanes. This proposed AD would require you to inspect the integral 
fuel tank wing ribs for cracks and the top and bottom wing skins for 
distortion and repair before further flight, and accomplish a fuel tank 
ventilating system installation. This proposed AD is the result of 
mandatory continuing airworthiness information (MCAI) issued by the 
airworthiness authority for Switzerland. The actions specified by this 
proposed AD are intended to detect and correct cracks in the ribs of 
the inboard integral fuel tanks in the left and right wings, which 
could lead to wing failure during flight.

DATES: The Federal Aviation Administration (FAA) must receive any 
comments on this proposed rule on or before May 12, 2003.

ADDRESSES: Submit comments to FAA, Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 2003-CE-12-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106. You may view any 
comments at this location between 8 a.m. and 4 p.m., Monday through 
Friday, except Federal holidays. You may also send comments 
electronically to the following address: [email protected]. 
Comments sent electronically must contain ``Docket No. 2003-CE-12-AD'' 
in the subject line. If you send comments electronically as attached 
electronic files, the files must be formatted in Microsoft Word 97 for 
Windows or ASCII text.
    You may get service information that applies to this proposed AD 
from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, 
Switzerland; telephone: +41 41 619 63 19; facsimile: +41 41 619 6224; 
or from Pilatus Business Aircraft Ltd., Product Support Department, 
11755 Airport Way, Broomfield, Colorado 80021; telephone: (303) 465-
9099; facsimile: (303) 465-6040. You may also view this information at 
the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Doug Rudolph, Aerospace Engineer, FAA, 
Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 
64106; telephone: (816) 329-4059; facsimile: (816) 329-4090.

SUPPLEMENTARY INFORMATION:

Comments Invited

    How do I comment on this proposed AD? The FAA invites comments on 
this proposed rule. You may submit whatever written data, views, or 
arguments you choose. You need to include the rule's docket number and 
submit your comments to the address specified under the caption 
ADDRESSES. We will consider all comments received on or before the 
closing date. We may amend this proposed rule in light of comments 
received. Factual information that supports your ideas and suggestions 
is extremely helpful in evaluating the effectiveness of this proposed 
AD action and determining whether we need to take additional rulemaking 
action.
    Are there any specific portions of this proposed AD I should pay 
attention to? The FAA specifically invites comments on the overall 
regulatory, economic, environmental, and energy aspects of this 
proposed rule that might suggest a need to modify the rule. You may 
view all comments we receive before and after the closing date of the 
rule in the Rules Docket. We will file a report in the Rules Docket 
that summarizes each

[[Page 16459]]

contact we have with the public that concerns the substantive parts of 
this proposed AD.
    How can I be sure FAA receives my comment? If you want FAA to 
acknowledge the receipt of your mailed comments, you must include a 
self-addressed, stamped postcard. On the postcard, write ``Comments to 
Docket No. 2003-CE-12-AD.'' We will date stamp and mail the postcard 
back to you.

Discussion

    What events have caused this proposed AD? The Federal Office for 
Civil Aviation (FOCA), which is the airworthiness authority for 
Switzerland, recently notified FAA that an unsafe condition may exist 
on all Pilatus Model PC-6 airplanes. The FOCA reports an incident where 
cracks have been found in the ribs of the inboard integral fuel tanks 
in the left and right wings of a Model PC-6 airplane. Investigation 
revealed that the cracks can occur when there are excessive pressure 
differentials between the ambient air pressure and that of the fuel 
tanks. The effect of this differential can be to compress the wing in 
the area of the fuel tank and cause distortion of the related 
structure. This distortion may result in fatigue cracks on ribs within 
the wing.
    What are the consequences if the condition is not corrected? These 
fatigue cracks on the ribs within the wing could lead to wing failure 
during flight.
    Is there service information that applies to this subject? Pilatus 
has issued the following:

--Service Bulletin (SB) No. 57-002, dated November 27, 2002; and
--SB No. 118, dated December 1972.

    What are the provisions of this service information? The service 
bulletins include procedures for:

--Inspecting the ribs in the left and right inboard fuel tanks;
--Repairing a rib;
--Inspecting to determine if the inboard fuel tank vent system is 
installed; and
--Installing the inboard fuel tank vent system.

    What action did the FOCA take? The FOCA classified this service 
bulletin as mandatory and issued Swiss AD Number HB 2003-092, dated 
February 17, 2003, in order to ensure the continued airworthiness of 
these airplanes in Switzerland.
    Was this in accordance with the bilateral airworthiness agreement? 
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 has 
kept FAA informed of the situation described above.

The FAA's Determination and an Explanation of the Provisions of This 
Proposed AD

    What has FAA decided? The FAA has examined the findings of the 
FOCA; reviewed all available information, including the service 
information referenced above; and determined that:

--The unsafe condition referenced in this document exists or could 
develop on other Pilatus Model PC-6 airplanes of the same type design 
that are on the U.S. registry;
--The actions specified in the previously-referenced service 
information should be accomplished on the affected airplanes; and
--AD action should be taken in order to correct this unsafe condition.

    What would this proposed AD require? This proposed AD would require 
you to incorporate the actions in the previously-referenced service 
bulletins.
    How does the revision to 14 CFR part 39 affect this proposed AD? On 
July 10, 2002, FAA published a new version of 14 CFR part 39 (67 FR 
47997, July 22, 2002), which governs FAA's AD system. This regulation 
now includes material that relates to special flight permits, 
alternative methods of compliance, and altered products. This material 
previously was included in each individual AD. Since this material is 
included in 14 CFR part 39, we will not include it in future AD 
actions.

Cost Impact

    How many airplanes would this proposed AD impact? We estimate that 
this proposed AD affects 35 airplanes in the U.S. registry.
    What would be the cost impact of this proposed AD on owners/
operators of the affected airplanes? We estimate the following costs to 
accomplish this proposed inspection:

----------------------------------------------------------------------------------------------------------------
                                                                Total cost
            Labor cost                      Parts cost             per          Total cost on U.S.  operators
                                                                 airplane
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5 workhours x $60 per hour = $300.  Not applicable...........         $300  $300 x 35 = $10,500.
----------------------------------------------------------------------------------------------------------------

    We estimate the following costs for each rib to accomplish any 
necessary rib repair that would be required based on the results of 
this proposed inspection. We have no way of determining the number of 
airplanes that may need such repair.

------------------------------------------------------------------------
                                                     Total cost per rib
          Labor cost                Parts cost          per airplane
------------------------------------------------------------------------
3 workhours x $60 per hour =    $50 per rib......  $230 per rib.
 $180 per rib.
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    We estimate the following costs to install any inboard fuel tank 
vent system that would be required based on the results of this 
proposed inspection. We have no way of determining the number of 
airplanes that may need such installation.

------------------------------------------------------------------------
                                                          Total cost per
               Labor cost                   Parts cost       airplane
------------------------------------------------------------------------
12 workhours x $60 per hour = $720......            $200            $920
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[[Page 16460]]

Regulatory Impact

    Would this proposed AD impact various entities? The regulations 
proposed herein would not have a substantial direct effect 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, it is determined that this 
proposed rule would not have federalism implications under Executive 
Order 13132.
    Would this proposed AD involve a significant rule or regulatory 
action? For the reasons discussed above, I certify that this proposed 
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, under 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. FAA amends Sec.  39.13 by adding a new airworthiness directive 
(AD) to read as follows:

Pilatus Aircraft Ltd.: Docket No. 2003-CE-12-AD

    (a) What airplanes are affected by this AD? This AD affects 
Model PC-6 airplanes, all manufacturer serial numbers (MSN) up to 
and including 939, that are certificated in any category.
    (b) Who must comply with this AD? Anyone who wishes to operate 
any of the airplanes identified in paragraph (a) of this AD must 
comply with this AD.
    (c) What problem does this AD address? The actions specified by 
this AD are intended to detect and correct cracks in the ribs of the 
inboard integral fuel tanks in the left and right wings, which could 
lead to wing failure during flight.
    (d) What actions must I accomplish to address this problem? To 
address this problem, you must accomplish the following:

------------------------------------------------------------------------
           Actions                 Compliance            Procedures
------------------------------------------------------------------------
(1) Inspect:
    (i) The ribs in the       Within the next 100   In accordance with
     inboard integral fuel     hours time-in-        Pilatus Aircraft
     tanks and related         service (TIS) after   Ltd. PC-6 Service
     structure in the left     the effective date    Bulletin No. 57-
     and right wings for       of this AD, unless    002, dated November
     crack damage;.            already               27, 2002, and the
                               accomplished.         applicable manual.
    (ii) The upper and lower
     wing skins for damage;
     and.
    (iii) To determine if
     the inboard fuel tank
     vent system is
     installed.
(2) If crack damage is
 found:
    (i) Correct the crack     Prior to further      In accordance with
     damage designated as      flight after the      Pilatus Aircraft
     repairable in the         inspections           Ltd. PC-6 Service
     service bulletin.         required in           Bulletin No. 57-
                               paragraph (d)(1) of   002, dated November
                               this AD.              27, 2002, and the
                                                     applicable
                                                     maintenance manual.
    (ii) For other crack
     damage, obtain a repair
     scheme from the
     manufacturer through
     FAA at the address
     specified in paragraph
     (e) of this AD and
     incorporate this repair
     scheme.
(3) If wing distortion is     Prior to further      In accordance with
 found, obtain a repair        flight after the      Pilatus Aircraft
 scheme from the               inspections           Ltd. PC-6 Service
 manufacturer through FAA at   required in           Bulletin No. 57-
 the address specified in      paragraph (d)(1) of   002, dated November
 paragraph (e) of this AD      this AD.              27, 2002, and the
 and incorporate this repair                         applicable
 scheme.                                             maintenance manual.
(4) If the inboard fuel tank  Prior to further      In accordance with
 vent system is not            flight after the      Pilatus Aircraft
 installed, install the        inspections           Ltd. PC-6 Service
 inboard fuel tank vent        required in           Bulletin No. 118,
 system.                       paragraph (d)(1) of   dated December
                               this AD.              1972, and the
                                                     applicable
                                                     maintenance manual.
------------------------------------------------------------------------

    (e) Can I comply with this AD in any other way? To use an 
alternative method of compliance or adjust the compliance time, 
follow the procedures in 14 CFR 39.19. Send these requests to the 
Manager, Standards Office, Small Airplane Directorate. For 
information on any already approved alternative methods of 
compliance, contact Doug Rudolph, Aerospace Engineer, FAA, Small 
Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 
64106; telephone: (816) 329-4059; facsimile: (816) 329-4090.
    (f) How do I get copies of the documents referenced in this AD? 
You may get copies of the documents referenced in this AD from 
Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, 
Switzerland; telephone: +41 41 619 63 19; facsimile: +41 41 619 
6224; or from Pilatus Business Aircraft Ltd., Product Support 
Department, 11755 Airport Way, Broomfield, Colorado 80021; 
telephone: (303) 465-9099; facsimile: (303) 465-6040. You may view 
these documents at FAA, Central Region, Office of the Regional 
Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

    Note: The subject of this AD is addressed in Swiss AD Number HB 
2003-092, dated February 17, 2003.


    Issued in Kansas City, Missouri, on March 28, 2003.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 03-8199 Filed 4-3-03; 8:45 am]
BILLING CODE 4910-13-P