AD 96-10-15

Events Leading to the AD A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to Piper Models PA31, PA31-300, PA31-325, and PA31-350 airplanes was published in the Federal Register on December 7, 1995 (60 FR 62779). The action proposed to supersede AD 80-14-06 with a new AD that would (1) retain the requirement of repetitively inspecting the outboard flap track, wing rib flanges, and the rear spar web at WS 147.5 for cracks, and, if any cracks are found, modifying the area at WS 147.5 by incorporating Piper Kit 763 986 as terminating action for the repetitive inspection requirement; and (2) require incorporating Piper Kit 763 986 at a specified hours TIS time-period for airplanes where no cracks were found during the inspections as terminating action for the repetitive inspection requirement. Accomplishment of the modification would be in accordance with the instructions included with Piper Kit 763 986, Revised April 15, 1991, as referenced in Piper SB No. 647A, dated November 24, 1980.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact The FAA estimates that 2,906 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 30 workhours per airplane to accomplish the required modification, and that the average labor rate is approximately $60 an hour. Parts cost approximately $468 per airplane. Based on these figures, the total cost impact of the required modification on U.S. operators is estimated to be $6,590,808 or $2,268 per airplane. This figure is based on the assumption that no affected airplane owner/operator has accomplished the required modification.

Piper has informed the FAA that parts have been distributed to enough owners/operators to equip 234 of the affected airplanes. Assuming that each set of parts has been installed on an affected airplane, the cost impact of this AD upon U.S. owners operators of the affected airplanes is reduced by $530,712 from $6,590,808 to $6,060,096.

The FAA's Aging Commuter Class Aircraft Policy This AD is part of the FAA's aging commuter class airplane policy, which briefly states that, when a modification exists that could eliminate or reduce the number of required critical inspections, the modification should be incorporated.

The intent of the FAA's aging commuter airplane program is toensure safe operation of commuter-class airplanes that are in commercial service without adversely impacting private operators. The FAA believes that a large number of the remaining 2,672 affected airplanes (2,906 airplanes - 234 sets of parts distributed) that will be affected by this AD are operated in various types of air transportation. This includes scheduled passenger service, air cargo, and air taxi.

This AD allows 1,000 hours time-in-service (TIS) after the effective date of the AD before mandatory accomplishment of the design modification. The average utilization of the fleet for those airplanes in air transportation is between 25 to 40 hours TIS per week. Based on these figures, operators of commuter-class airplanes involved in commercial operation will have to accomplish the required modification within 6 to 10 months after this AD becomes effective. For private owners, who typically operate between 100 to 200 hours TIS per year, this allows 5 to 10 years before therequired modification is mandatory.

The FAA established the 1,000 hours TIS modification compliance time based on its engineering evaluation of the problem. Among the issues examined during this engineering evaluation were analysis of service difficulty reports, the difficulty level of the inspection, and how critical the situation would be if cracks occurred in the subject area despite accomplishment of the repetitive inspections.

Usually, the FAA establishes the mandatory design modification compliance time on AD's affecting aging commuter-class airplanes upon the accumulation of a certain number of hours TIS on the airplane. For this action, the FAA is mandating the modification for all operators "within the next 1,000 hours TIS after the effective date of this AD." The total TIS levels of the airplane fleet vary from under 1,000 hours TIS to over 5,000 hours TIS, and annual accumulation rates vary from 50 hours TIS to over 1,000 hours TIS. Establishing a long-term setcompliance time of hours TIS accumulated on a Piper Model PA31, PA31-300, PA31-325, or PA31-350 airplane (such as 5,000 hours TIS) imposes an undue burden on the manufacturer of having to maintain a supply of replacement parts for the entire fleet when many airplanes in the fleet may never reach this compliance time.

Instead, the FAA believes that Piper should maintain parts for several years; in this case about 10 years to allow low-usage airplanes time to accumulate the "1,000 hours TIS after the effective date of the AD." The FAA has determined that the compliance time of this AD provides the level of safety required for commuter air service while still minimizing the impact on the private airplane owners of Piper Models PA31, PA31-300, PA31-325, and PA31-350 airplanes.

Regulatory Impact The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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, pursuant to 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 USC 106(g), 40113, 44701.

Section 39.13 - [AMENDED] 2. Section 39.13 is amended by removing Airworthiness Directive (AD) 80-14-06, Amendment 39-3805, and by adding a new AD to read as follows: