[Federal Register Volume 71, Number 179 (Friday, September 15, 2006)]
[Proposed Rules]
[Pages 54441-54443]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-15342]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-25582; Directorate Identifier 2006-CE-42-AD]
RIN 2120-AA64


Airworthiness Directives; Pilatus Aircraft Ltd. Model PC-7 
Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Pilatus Aircraft Ltd. (Pilatus) Model PC-7 airplanes. This 
proposed AD would require you to do repetitive eddy-current, non-
destructive inspections of the nose skin and adjacent structure above 
the left and right main landing gear bay and repetitive visual 
inspections of the forward support structure of the floor panel for 
crack damage. If you find any crack damage, this proposed AD would 
require you to contact Pilatus to obtain a repair solution and 
incorporate the repair. This proposed AD results from mandatory 
continuing airworthiness information (MCAI) issued by the airworthiness 
authority for Switzerland. We are proposing this AD to detect and 
correct cracks in the nose skin and adjacent structure above the left 
and right main landing gear bay and in the forward support structure of 
the floor panel. Crack propagation in certain areas could lead to 
failure of the main wing torsion box, which could result in loss of 
control.

DATES: We must receive comments on this proposed AD by October 16, 
2006.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, 
Switzerland; telephone: +41 41 619 63 19; fax: +41 41 619 6224.

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

    We invite you to send any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include the docket number, ``FAA-
2006-25582; Directorate Identifier 2006-CE-42-AD'' at the beginning of 
your comments. We specifically invite comments on the overall 
regulatory, economic, environmental, and energy aspects of the proposed 
AD. We will consider all comments received by the closing date and may 
amend the proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact we 
receive concerning this proposed AD.

Discussion

    The Federal Office for Civil Aviation (FOCA), which is the 
airworthiness authority for Switzerland, notified FAA that an unsafe 
condition may exist on certain Pilatus PC-7 airplanes. The FOCA reports 
crack damage in some radii at the rear edge of the nose skin, part 
number (P/N) 111.34.07.434. The radii are adjacent to the left and 
right corners at the forward edge of the floor panel, P/N 
111.34.07.530. Crack damage can also occur in the forward support 
structure of the floor panel adjacent to the skin panel.
    This condition, if not detected and corrected, could result in 
crack propagation in certain areas, which may lead to failure of the 
main wing torsion box. This failure could result in loss of control.

Relevant Service Information

    We have reviewed Pilatus PC-7 Service Bulletin No. 57-009, dated 
January 29, 2004. The service information describes procedures for 
visually inspecting the forward support

[[Page 54442]]

structure of the floor panel and eddy-current, non-destructive 
inspecting the nose skin and adjacent structure above the left and 
right main landing gear bay for crack damage.

Foreign Airworthiness Authority Information

    The FOCA classified this service bulletin as mandatory and issued 
Swiss AD HB 2006-374, effective date August 2, 2006, to ensure the 
continued airworthiness of these airplanes in Switzerland.
    These Pilatus PC-7 airplanes are manufactured in Switzerland and 
are type-certificated for operation in the United States under the 
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 
21.29) and the applicable bilateral airworthiness agreement.
    Under this bilateral airworthiness agreement, the FOCA has kept us 
informed of the situation described above.

FAA's Determination and Requirements of the Proposed AD

    We are proposing this AD because we have examined the FOCA's 
findings, evaluated all information and determined the unsafe condition 
described previously is likely to exist or develop on other products of 
the same type design that are certificated for operation in the United 
States.
    This proposed AD would require you to do repetitive eddy-current, 
non-destructive inspections of the nose skin and adjacent structure 
above the left and right main landing gear bay and repetitive visual 
inspections of the forward support structure of the floor panel for 
crack damage. If you find any crack damage, this proposed AD would 
require you to contact Pilatus to obtain a repair solution and 
incorporate the repair.

Differences Between the FOCA AD, the Service Information, and This 
Proposed AD

    FOCA AD HB-2006-374, effective date August 2, 2006, allows 
continued flight if cracks are found in the nose skin that do not 
exceed certain limits. The applicable service bulletin specifies repair 
of the nose skin only if cracks are found exceeding limits illustrated 
in Pilatus PC-7 Service Bulletin No. 57-009, dated January 29, 2004, as 
does FOCA AD HB-2006-374, effective date August 2, 2006. This proposed 
AD, if adopted, does not allow continued flight if any crack is found. 
FAA policy is to disallow airplane operation when known cracks exist in 
primary structure, unless the ability to sustain ultimate load with 
these cracks is proven. The nose skin is considered primary structure, 
and the FAA has not received any analysis to prove that ultimate load 
can be sustained with cracks in this area.
    The requirements of this proposed AD, if adopted as a final rule, 
would take precedence over the provisions in the service information.

Costs of Compliance

    We estimate that this proposed AD would affect 10 airplanes in the 
U.S. registry.
    We estimate the following costs to do the proposed inspection:

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                                                                                    Total cost  on
              Labor cost                      Parts cost          Total cost  per        U.S.
                                                                      airplane         operators
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3 work-hours x $80 per hour = $240...  No parts required.......               $240          $2,400
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    Any required ``upon-condition'' repairs would vary depending upon 
the damage found. Based on this, we have no way of determining the 
potential repair costs for each airplane or the number of airplanes 
that would need the repairs based on the result of the proposed 
inspections.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the proposed 
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order 
12866;
    2. Is not a ``significant rule'' under the 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket.

Examining the AD Docket

    You may examine the AD docket that contains the proposed AD, the 
regulatory evaluation, any comments received, and other information on 
the Internet at http://dms.dot.gov; or in person at the Docket 
Management Facility between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Office (telephone (800) 647-5227) 
is located at the street address stated in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

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 FAA proposes to amend 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 54443]]

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new AD:

Pilatus Aircraft Ltd.: Docket No. FAA-2006-25582; Directorate 
Identifier 2006-CE-42-AD.

Comments Due Date

    (a) We must receive comments on this airworthiness directive 
(AD) action by October 16, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model PC-7 airplanes, manufacturer serial 
numbers 101 through 618 inclusive, that are certificated in any 
category.

Unsafe Condition

    (d) This AD results from mandatory continuing airworthiness 
information (MCAI) issued by the airworthiness authority for 
Switzerland. We are issuing this AD to detect and correct cracks in 
the nose skin and adjacent structure above the left and right main 
landing gear bay and in the forward support structure of the floor 
panel. Crack propagation in certain areas could lead to failure of 
the main wing torsion box. This failure could result in loss of 
control.

Compliance

    (e) To address this problem, you must do the following:

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           Actions                 Compliance            Procedures
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(1) Inspect:                  Initially inspect     Do the initial
(i) The forward area of the    within the next 150   inspection
 floor panel and the related   hours time-in-        following Pilatus
 structure for cracks using    service or 6          PC-7 Service
 magnified, visual methods.    calendar months,      Bulletin No. 57-
(ii) The nose skin and         whichever occurs      009, dated January
 adjacent structure above      first, after the      29, 2004. Do the
 the left and right main       effective date of     repetitive
 landing gear bay for cracks   this AD, unless       inspections
 using eddy-current, non-      already done.         following the
 destructive methods.          Repetitively          procedures in AMM
                               inspect thereafter    57-10-03, dated
                               at intervals          March 4, 2005, and
                               specified in          AMM 05-30-05, dated
                               paragraph 2. B. of    February 28, 2006.
                               Pilatus PC-7
                               Aircraft
                               Maintenance Manual
                               (AMM) 05-10-00,
                               dated March 4, 2005.
(2) If crack damage is found  Before further        Obtain an FAA-
 during any inspection         flight after any      approved repair
 required by paragraph         inspection in which   solution from the
 (e)(1) of this AD, obtain     crack damage is       manufacturer
 an FAA-approved repair        found. Further        through the FAA at
 solution from the             flight with crack     the address
 manufacturer through the      damage is not         specified in
 FAA at the address            permitted. After      paragraph (f) of
 specified in paragraph (f)    incorporating the     this AD and
 of this AD and incorporate    repair,               incorporate the
 the repair.                   repetitively          repair.
                               inspect as
                               specified in
                               paragraph (e)(1) of
                               this AD.
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Alternative Methods of Compliance (AMOCs)

    (f) The Manager, Standards Staff, FAA, ATTN: Doug Rudolph, 
Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, 
Room 301, Kansas City, Missouri 64106; telephone: (816) 329-4059; 
facsimile: (816) 329-4090, has the authority to approve AMOCs for 
this AD, if requested using the procedures found in 14 CFR 39.19.

Related Information

    (g) The Federal Office for Civil Aviation Swiss AD HB-2006-374, 
effective date August 2, 2006, also addresses the subject of this 
AD. To get copies of the service information referenced in this AD, 
contact Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 
Stans, Switzerland; telephone: +41 41 619 63 19; fax: +41 41 619 
6224. To view the AD docket, go to the Docket Management Facility; 
U.S. Department of Transportation, 400 Seventh Street, SW., Nassif 
Building, Room PL-401, Washington, DC, or on the Internet at http://dms.dot.gov. The docket number is Docket No. FAA-2006-25582; 
Directorate Identifier 2006-CE-42-AD.

    Issued in Kansas City, Missouri, on September 11, 2006.
John R. Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-15342 Filed 9-14-06; 8:45 am]
BILLING CODE 4910-13-P