Airworthiness Directives; Pilatus Aircraft Ltd. Models PC-7, PC-12, and PC-12/45 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 all Pilatus Aircraft Ltd. Models PC-7, PC-12, and PC-12/45 airplanes that incorporate a certain engine-driven pump. This proposed AD would require you to: inspect the joints between the engine-driven pump housing, relief valve housing, and the relief-valve cover for signs of fuel leakage or extruding gasket material; replace any engine-driven pump with signs of fuel leakage or extruding gasket material; and inspect to ensure that the relief valve attachment screws are adequately torqued and re-torque as necessary. 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 gasket material extruding from the engine-driven pump housing and detect and correct relief valve attachment screws with inadequate torque. Such conditions could lead to fuel leakage and result in a fire in the engine compartment.

DATES:

The Federal Aviation Administration (FAA) must receive any comments on this proposed rule on or before November 30, 2001.

ADDRESSES:

Submit comments to FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2001-CE-33-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 get information that applies to the 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 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 comments, you must include a self-addressed, stamped postcard. On the postcard, write “Comments to Docket No. 2001-CE-33-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 of an unsafe condition that may exist on Pilatus Models PC-7, PC-12, and PC-12/45 airplanes. The FOCA reports instances of fuel leaking from the engine-driven pump on the referenced airplanes. The compression set of the gasket and diaphragm after thermal cycling could cause the gasket of the engine-driven pump to extrude between the relief valve housing and the engine-driven pump housing. This in turn relieves the torque of the relief-valve cover screws of the engine-driven pump, which could result in fuel leakage.

Information on the affected pumps follows:

—The affected engine-driven pumps are Lear Romec part number RG9570R1 (Pilatus part number 968.84.51.106) as installed on Models PC-12 and PC-12/45 airplanes or Lear Romec part number RG9570M1 (Pilatus part number 968.84.51.105) as installed on Model PC-7 airplanes;

—Pilatus installed these engine-driven pumps on manufacturer serial number (MSN) 101 through MSN 400 of the Models PC-12 and PC-12/45 airplanes and MSN 101 through MSN 618 of the Model PC-7 airplanes; and

—These engine-driven pumps could be installed through field approval on any MSN of the Models PC-7, PC-12, and PC-12/45 airplanes.

What are the consequences if the condition is not corrected? Gasket material extruding from the engine-driven pump housing and relief valve attachment screws with inadequate torque, if not detected and corrected, could lead to fuel leakage and result in a fire in the engine compartment.

Is there service information that applies to this subject? Pilatus has issued the following:

—Service Bulletin No. 28-006, dated August 10, 2001, which applies to the Model PC-7 airplanes; and

—Service Bulletin No. 28-009, dated August 10, 2001, which applies to the Models PC-12 and PC-12/45 airplanes.

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

—Inspecting the joints between the engine-driven pump housing, relief valve housing, and the relief-valve cover for signs of fuel leakage or extruding gasket material;

—Replacing any engine-driven pump with signs of fuel leakage or extruding gasket material; and

—Inspecting to ensure that the relief valve attachment screws are adequately torqued and re-torque as necessary.

What action did the FOCA take? The FOCA classified this service bulletin as mandatory and issued Swiss AD HB 2001-500 (PC-12 and PC-12/45) and Swiss AD HB-505 (PC-7), both dated August 24, 2001, 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 Models PC-7, PC-12, and PC-12/45 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 278 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 the proposed inspections and re-torque:

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:

Compliance Time of This Proposed AD

What would be the compliance time of this proposed AD? The compliance time of the inspections that would be required by the proposed AD is “within 20 hours time-in-service (TIS) after the effective date of this AD or within the next 30 days after the effective date to this AD, whichever occurs first.”

Why is the compliance time of this proposed AD presented in both hours TIS and calendar time? The deterioration and potential extrusion of the gasket occurs over time and is not a condition of repetitive airplane operation. However, the relief valve attachment screws becoming inadequately torqued occurs as a result of airplane usage if the compression set of the gasket and diaphragm after thermal cycling causes the gasket of the engine-driven pump to extrude between the relief valve housing and the engine-driven pump housing.

Therefore, to ensure that the unsafe condition defined in this document is detected and corrected in a timely manner, we are proposing the compliance in both calendar time and hours TIS.

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.