AD 98-09-25

This amendment adopts a new airworthiness directive (AD) that applies to certain The New Piper Aircraft, Inc. (Piper) Models PA-31, PA-31-300, PA-31-325, and PA-31-350 airplanes. This AD requires replacing the lower spar splice plate and reworking the lower spar caps. This AD results from numerous reports of fretting and cracking of the lower spar splice plates on Piper PA-31 series airplanes in Australia, and a report of one incident in the United States. The actions specified by this AD are intended to prevent failure of the lower spar splice plate caused by fretting and cracking, which could result in loss of control of the airplane.

Final rule

98-09-25 THE NEW PIPER AIRCRAFT, INC.: Amendment 39-10506; Docket No. 97-CE-48-AD.

Applicability: The following airplane model and serial numbers, certificated in any category:

Models
Serial Numbers
PA-31, PA-31-300, and PA-31-325
31-2 through 31-8312019
PA-31-350
31-5001 through 31-8553002

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, 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 (c) 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 the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
Compliance: Required as follows, unless already accomplished:

1. For the affected Models PA-31, PA-31-300, and PA-31-325 airplanes: Upon accumulating 6,000 hours on the lower spar splice plate or within the next 100 hours time-in-service (TIS) after the effective date of this AD, whichever occurs later; and

2. For the affected Model PA-31-350 airplanes: Upon accumulating 13,000 hours TIS on the lower spar splice plate or within the next 100 hours TIS after the effective date of this AD, whichever occurs later.

To prevent failure of the lower spar splice plate caused by fretting and cracking, which could result in loss of control of the airplane, accomplish the following:

(a) Replace the lower spar splice plate and rework the lower spar caps in accordance with the instructions included in the following kits, as applicable, and as referenced in Piper Service Bulletin No. 1003, dated June 16, 1997:

(1) Main Spar Splice Plate Replacement (Lower) Kit No. 766-640, Drawing 88254, Revision A, dated May 12, 1997, which applies to Models PA-31, PA-31-300, and Piper PA-31-325 airplanes; and

(2) Main Spar Splice Plate Replacement (Lower) Kit No. 766-641, Drawing 88255, Revision A, dated May 12, 1997, which applies to Model PA-31-350 airplanes.

(b) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(c) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Atlanta Aircraft Certification Office (ACO), 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

(d) The replacements required by this AD shall be done in accordance with the instructions to Piper Main Spar Splice Plate Replacement (Lower) Kit No. 766-641, Drawing 88255, Revision A, dated May 12, 1997; or Piper Main Spar Splice Plate Replacement (Lower) Kit No. 766-640, Drawing 88254, Revision A, dated May 12, 1997. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from The New Piper Aircraft, Inc., 2926 Piper Drive, Vero Beach, Florida 32960. Copies may be inspected at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

(e) This amendment becomes effective on June 15, 1998.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Piper Models PA-31, PA-31-300, PA-31-325, and PA-31-350 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on August 22, 1997 (62 FR 44597). The NPRM proposed to require replacing the lower spar splice plate and reworking the lower spar caps. Accomplishment of the proposed action as specified in the NPRM would be required in accordance with Piper Main Spar Splice Plate Replacement (Lower) Kit No. 766-641, Drawing 88255, Revision A, dated May 12, 1997; or Piper Main Spar Splice Plate Replacement (Lower) Kit No. 766-640, Drawing 88254, Revision A, dated May 12, 1997.

The NPRM was the result of numerous reports of fretting and cracking of the lower spar splice plates on Piper PA-31 series airplanes in Australia, and a report of one incident in the United States.

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.

The FAA has received data from the Australian Civil Aviation Safety Authority (CASA), which was based on the analysis of 34 airplanes. This data shows the lower spar splice plate replacement threshold as the following:

- 6,000 hours time-in-service (TIS) for Models PA-31, PA-31-300, and PA-31-325 airplanes; and

- 13,000 hours TIS for Model PA-31-350 airplanes.

The lower spar splice plate replacement threshold was presented as 2,500 hours TIS in the NPRM. The FAA conducted statistical analysis on this data received from the Australian CASA. This analysis shows that the thresholds presented by the Australian CASA are reliable and accurate.

The FAA's Determination
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 the change in the compliance time (from 2,500 hours TIS to 6,000 hours TIS or 13,000 hours TIS, as applicable) and 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 1,700 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 8 workhours per airplane to accomplish this replacement, and that the average labor rate is approximately $60 an hour. Parts cost approximately $210 per airplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $1,173,000, or $690 per airplane.

Piper has informed the FAA that, as of August 22, 1997 (the publication date of the NPRM), parts have been distributed to equip 1 affected airplane. Presuming that this set of parts is installed on an affected airplane, the cost impact of this AD will be reduced by $690, from $1,173,000 to $1,172,310.

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 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: