Discussion
What Events Have Caused This 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 Is the Potential Impact if FAA Took No Action?
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.
Has FAA Taken Any Action to This Point?
We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an 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 proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on October 24, 2001 (66 FR 53738). The NPRM proposed to 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.
Was the Public Invited To Comment?
The FAA encouraged interested persons to participate in the making of this amendment. We did not receive any comments on the proposed rule or on our determination of the cost to the public.
FAA's Determination
What Is FAA's Final Determination on This Issue?
After careful review of all available information related to the subject presented above, we have determined that air safety and the public interest require the adoption of therule as proposed except for minor editorial corrections. We have determined that these minor corrections:
--Provide the intent that was proposed in the NPRM for correcting the unsafe condition; and
--Do not add any additional burden upon the public than was already proposed in the NPRM.
Cost Impact
How Many Airplanes Does This AD Impact?
We estimate that this AD affects 278 airplanes in the U.S. registry.
What Is the Cost Impact of This AD on Owners/Operators of the Affected Airplanes?
We estimate the following costs to accomplish the inspections and re-torque:
Labor cost
Parts cost
Total cost per airplane
Total cost on U.S. operators
2 workhours x $60 per hour = $120
Not Applicable
$120
$120 x 278 = $33,360.
We estimate the following costs to accomplish any necessary replacements that will be required based on the results of the inspection. We have no way of determining the number of airplanes that may need such replacement:Labor cost
Parts cost
Total cost per airplane
1 workhour X $60 per hour = $60
$3,900 per new pump
$3,960 per airplane.
Compliance Time of This AD
What Is the Compliance Time of This AD?
The compliance time of the inspections that will be required by this 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 of this AD, whichever occurs first."
Why Is the Compliance Time of This 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 ensurethat the unsafe condition defined in this document is detected and corrected in a timely manner, we are stating the compliance in both calendar time and hours TIS.
Regulatory Impact
Does This AD Impact Various Entities?
The regulations adopted herein will 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 final rule does not have federalism implications under Executive Order 13132.
Does This AD Involve a Significant Rule or Regulatory Action?
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, under 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. FAA amends Sec. 39.13 by adding a new AD to read as follows: