AD 2003-20-05

This AD becomes effective on November 14, 2003.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulation as of November 14, 2003.

You may get the service information identified 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 the AD docket at FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-CE-29-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. Office hours are 8 a.m. to 4 p.m., Monday through Friday, except Federal holidays.

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

What Events Have Caused This 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 dihedral fittings, reported a crack in one fitting. An inspection of the fleet revealed stress corrosion cracking in six aft dihedral fittings. Each cracked fitting was found on airplanes that had logged more than 3,000 hours time-in-service (TIS) or had been in service for 10 years or more.

What Is the Potential Impact if FAA Took No Action?

Cracks in the forward and aft dihedral fittings could result in failure of the wing in certain maneuvers. Such failure could lead to loss of control of the airplane.

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 certain Pilatus Model PC-7 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on July 3, 2003 (68 FR 398970). The NPRM proposed to require you to:

—Inspect the forward and aft dihedral fittings for cracks;

—Replace any cracked fittings found; and

—Modify the aft dihedral fittings and spar-cap bolt holes.

Was the Public Invited To Comment?

We provided the public the opportunity to participate in the development of this AD. We received no comments on the proposal or on the determination of the cost to the public.

What Is FAA's Final Determination on This Issue?

We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD 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.

How Does the Revision to 14 CFR Part 39 Affect This AD?

On July 10, 2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. 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.

How Many Airplanes Does This AD Impact?

We estimate that this AD affects 10 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 actions of this AD:

What Is the Compliance Time of This AD?

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

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

Cracking of the dihedral fittings 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 used.

Will This AD Impact Various Entities?

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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.

Will This AD Involve a Significant Rule or Regulatory Action?

For the reasons discussed above, I certify that this AD:

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 summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-CE-29-AD” in your request.

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:

1. The authority citation for part 39 continues to read as follows:

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