02-20136. Airworthiness Directives; PILATUS Aircraft Ltd. Model PC-7 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to adopt a new airworthiness directive (AD) that would apply to certain PILATUS Aircraft Ltd. (Pilatus) Model PC-7 airplanes. This proposed AD would require you to repetitively inspect the main landing gear front attachment brackets for cracks, and, if cracks are found, install improved-design brackets. Installing the improved-design brackets terminates the required inspections. 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 main landing gear front attachment brackets, which could result in failure of the brackets. Such failure could lead to the main landing gear leg detaching from the wing main spar.

DATES:

The Federal Aviation Administration (FAA) must receive any comments on this proposed rule on or before September 20, 2002.

ADDRESSES:

Submit comments to FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-CE-28-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: [e-mail]. Comments sent electronically must contain “Docket No. 2002-CE-28-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: [phone]; facsimile: [phone]; or from Pilatus Business Aircraft Ltd., Product Support Department, 11755 Airport Way, Broomfield, Colorado 80021; telephone: [phone]; facsimile: [phone]. 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: [phone]; facsimile: [phone].

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 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. 2002-CE-28-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 certain Pilatus Model PC-7 airplanes. The FOCA reports that an operator of a similar aircraft type design, which uses identical main landing gear support brackets, reported a single crack in one bracket. A fleet inspection of the operator's aircraft revealed stress corrosion cracking in more than 20 aircraft.

What Are the Consequences if the Condition Is Not Corrected?

Cracks in the main landing gear front attachment brackets could result in failure of the brackets. Such failure could lead to the main landing gear leg detaching from the wing main spar.

Is There Service Information That Applies to This Subject?

Pilatus has issued:

—Pilatus PC-7 Service Bulletin No. 57-004, Revision No. 1, dated June 17, 2002;

—Pilatus PC-7 Service Bulletin No. 57-005, dated September 10, 2001; and

—Pilatus PC-7 Maintenance Manual, Temporary Revision No. 05-10, dated September 10, 2001.

What Are The Provisions of This Service Information?

The service information includes procedures for:

—inspection of the main landing gear front attachment brackets; and

—replacement of the main landing gear front attachment bracket.

What Action Did the FOCA Take?

The FOCA classified this service information as mandatory and issued Swiss AD Number HB 2002-270, dated June 24, 2002, in order to ensure the continued airworthiness of these airplanes in Switzerland.

Was This in Accordance With the Bilateral Airworthiness Agreement?

These airplane models 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.

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-7 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 bulletin.

Cost Impact

How Many Airplanes Would This Proposed AD Impact?

We estimate that this proposed AD affects 14 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 each proposed inspection:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
4 workhours × $60 = $240	No parts required	$240	$240 × 14 = $3,360.

The FAA has no method of determining the number of repetitive inspections each owner/operator would incur over the life of each of the affected airplanes so the cost impact is based on the initial inspection.

We estimate the following costs to accomplish any necessary replacements that would be required based on the results of the proposed inspection. We have no way of determining the number of airplanes that may need such replacement:

Labor cost	Parts cost	Total cost per airplane
80 workhours × $60 = $4,800 per side	$2,500 per side	$4,800 + $2,500 = $7,300 per side.

Compliance Time of This Proposed AD

What Would Be the Compliance Time of This Proposed AD?

The compliance time of this proposed AD is whichever occurs later: (1) upon the accumulation of 3,000 hours time-in-service (TIS) on the attachment brackets or 10 years after installation of the brackets, whichever occurs first; or (2) within 90 days after the effective date of the proposed AD.

Why Is the Compliance Time of This Proposed AD Presented in Both Hours TIS and Calendar Time?

Cracking of the main landing gear attachment brackets on the affected airplanes is caused by stress corrosion, which starts as a result of high local stress incurred through operation. Corrosion can then develop regardless of whether the airplane is in flight or on the ground. The cracks may not be noticed initially as a result of the stress loads, but could then progress as a result of corrosion. The stress incurred during flight operations or temperature changes could then cause rapid crack growth. In order to ensure that these stress corrosion cracks do not go undetected, a compliance time of specific hours TIS and calendar time is utilized.

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.

§ 39.13

[Amended]

2. FAA amends § 39.13 by adding a new airworthiness directive (AD) to read as follows:

Pilatus Aircraft Ltd.: Docket No. 2002-CE-28-AD

(a) What airplanes are affected by this AD? This AD affects Model PC-7 airplanes, serial numbers 101 through 618, 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 main landing gear front attachment brackets, which could result in failure of the brackets. Such failure could lead to the main landing gear leg detaching from the wing main spar.

(d) What actions must I accomplish to address this problem? To address this problem, you must accomplish the following:

Compliance	Actions	Procedures
(1) Initial Inspection: At whichever of the following occurs later, unless already accomplished: (i) upon the accumulation of 3,000 hours time-in-service (TIS) on the attachment brackets or 10 years after installation of the brackets, whichever occurs first; or (ii) within 90 days after the effective date of this AD.	Inspect, using the Impedance-Plane Eddy-Current Inspection, both main landing gear front attachment brackets, part number (P/N) 111.34.07.105 and P/N 111.34.07.106 for cracks	In accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus PC-7 Service Bulletin No. 57-004, Revision No. 1, dated June 17, 2002; the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus PC-7 Service Bulletin No. 57-005, dated September 10, 2001; and Pilatus PC-7 Maintenance Manual, Temporary Revision No. 05-10, dated September 10, 2001.
(2) Repetitive Inspections: Within 12 calendar months after the initial inspection required in paragraph (d)(1) of this AD and thereafter at intervals not to exceed 12 calendar months	Inspect, using the Impedance-Plane Eddy-Current Inspection, both main landing gear front attachment brackets, P/N 111.34.07.105 and P/N 111.34.07.106 for cracks	In accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus PC-7 Service Bulletin No. 57-004, Revision No. 1, dated June 17, 2002; the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus PC-7 Service Bulletin No. 57-005, dated September 10, 2001; and Pilatus PC-7 Maintenance Manual, Temporary Revision No. 05-10, dated September 10, 2001.
(3) Prior to further flight after the inspection which the damage was found	If a crack is found in any main landing gear front attachment bracket during any inspection required in this AD, replace with an improved bracket, P/N 557.10.09.045, P/N 557.10.09.046, or FAA-approved equivalent P/N. Repetitive inspections are still required on any P/N 111.34.07.105 and P/N 111.34.07.106 for cracks	In accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus PC-7 Service Bulletin No. 57-005, dated September 10, 2001.
(4) At any time terminating action for the repetitive inspections. However, you must replace prior to further flight if you find cracks during any inspections required by this AD	You may terminate the inspections required in paragraphs(d)(1) and (d)(2) of this AD when improved design main landing gear front attachment brackets, P/N 557.10.09.045, P/N 557.10.09.046, or FAA-approved equivalent P/Ns, are installed on both sides of the airplane	In accordance with ACCOMPLISHMENT INSTRUCTIONS Pilatus PC-7 Service Bulletin No. 57-005, dated September 10, 2001.
(5) As of the effective date of this AD	Only install main landing gear brackets that are P/N 557.10.09.045, P/N 557.10.09.046, or FAA-approved equivalent P/Ns	Not Applicable.

Note 1:

If you find cracks on one side only, you are only required to replace the damaged side with the new improved-design bracket and continue the repetitive inspections required by paragraph (d)(2) of this AD. Repetitive inspections are still required on any installed bracket with either P/N 111.34.07.105 or P/N 111.34.07.106.

(e) Can I comply with this AD in any other way? You may use an alternative method of compliance or adjust the compliance time if:

(1) Your alternative method of compliance provides an equivalent level of safety; and

(2) The Standards Office Manager, Small Airplane Directorate, approves your alternative. Submit your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Standards Office Manager.

Note 2:

This AD applies to each airplane identified in paragraph (a) of this AD, 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 (e) 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 you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about 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: [phone]; facsimile: [phone].

(g) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD.

(h) 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: [phone]; facsimile: [phone]; or from Pilatus Business Aircraft Ltd., Product Support Department, 11755 Airport Way, Broomfield, Colorado 80021; telephone: [phone]; facsimile: [phone]. You may view these documents at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

Note 3:

The subject of this AD is addressed in Swiss AD HB 2002-270, dated June 24, 2002.

Issued in Kansas City, Missouri, on August 2, 2002.

Dorenda D. Baker,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.