AD 94-13-11

This amendment adopts a new airworthiness directive (AD) that applies to certain Piper Aircraft Corporation (Piper) Models PA34-200, PA34-200T, PA34-220T, PA44-180, and PA44-180T airplanes. This action requires repetitively inspecting the main landing gear trunnions for cracks, replacing any trunnions found cracked, and eventually replacing these trunnions with improved parts as terminating action for the repetitive inspection requirement. Several reports of the main landing gear trunnions cracking on the affected airplanes prompted this action. The actions specified by this AD are intended to prevent collapse of the main landing gear caused by cracked trunnions, which could result in airplane damage.

Final rule.

94-13-11 PIPER AIRCRAFT CORPORATION: Amendment 39-8952; Docket No. 93-CE-58 -AD.

Applicability: The following model and serial number airplanes that are not equipped with main landing gear (MLG) trunnions (both left and right side) that have either part number (P/N) 67926-30, 67926-31, 67926-32, 67926-33, 39486-14, or 39486-15, as applicable, certificated in any category:

Models
Serial Numbers
PA34-200
34-7250001 through 34-7450220
PA34-200T
34-7570001 through 34-8170092
PA34-220T
34-8133001 through 34-8233088 that are not
equipped with trunnion housing assemblies,
Piper part number 39486-802 (left) and
39486-803 (right) with embossed forging
number 67924-2
PA44-180
44-7995001 through 44-8195026, and
4495001 through 4495013
PA44-180T
44-8107001 through 44-8207020

Compliance: Required as indicated, unless already accomplished.

To prevent collapse of the main landing gear caused by cracked trunnions, which could result in airplane damage, accomplish the following:

NOTE 1: The paragraph structure of this AD is as follows:

Level 1:
(a), (b), (c), etc.
Level 2:
(1), (2), (3), etc.
Level 3:
(i), (ii), (iii), etc.

Level 2 and Level 3 structures are designations of the Level 1 paragraph they immediately follow.

(a) Upon the accumulation of 500 hours time-in-service (TIS) on a MLG trunnion, dye-penetrant inspect the MLG trunnion for cracks in accordance with the INSTRUCTIONS section of Piper Service Bulletin (SB) No. 787B, dated August 25, 1993.

NOTE 2: If hours TIS on the MLG trunnion are unknown, hours TIS accumulated on the airplane may be substituted.

(1) Prior to further flight, blend out any grinding marks in the web area (depicted in the sketches of the SB referenced above), using aluminum oxide paper, 300 grit (or finer), or an equivalent material. Alodine and repaint areas where grinding marks are blended out.

(2) For MLG trunnions found cracked, prior to further flight, replace the cracked MLG trunnion with a part of improved design, P/N 67926-30, 67926-31, 67926-32, 67926-33, 39486-14, or 39486-15, as applicable, in accordance with the applicable maintenance manual.

(3) For MLG trunnions not found cracked, reinspect at intervals not to exceed 100 hours TIS until the replacement specified in paragraph (b) of this AD is accomplished.

(4) If one trunnion is found cracked and is replaced as specified in paragraph (a)(2) of this AD, the other trunnion must still be reinspected as specified in paragraph (a)(3) of this AD until it also is replaced.

(b) Upon the accumulation of 2,000 hours TIS on a MLG trunnion or within the next 100 hours TIS after the effective date of this AD, whichever occurs later, unless already accomplished as specified in paragraph (a)(2) of this AD, replace each MLG trunnion with a part of improved design, P/N 67926-30, 67926-31, 67926-32, 67926-33, 39486-14, or 39486-15, as applicable, in accordance with the applicable maintenance manual.

(1) If parts for any MLG replacement have been ordered from the manufacturer but are not available, prior to further flight and thereafter at intervals not to exceed 100 hour TIS, dye-penetrant inspect the MLG trunnion for cracks in accordance with the INSTRUCTIONS section of Piper No. SB 787B, dated August 25, 1993. If any one of the following occurs, prior to further flight, terminate the above repetitive inspections and replace the trunnion as specified in paragraph (b) of this AD:

(i) Parts become available;

(ii) A trunnion is found cracked; or

(iii) 2,500 hours TIS are accumulated on the trunnion or 500 hours TIS after the effective date of this AD, whichever occurs later.

(2) Replacing both the left and right MLG trunnion with P/N 67926-30, 67926-31, 67926-32, 67926-33, 39486-14, or 39486-15, as applicable, eliminates the inspection requirement of this AD.

(c) 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.

(d) 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), 1669 Phoenix Parkway, Suite 210C, 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 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

(e) The inspections required by this AD shall be done in accordance with Piper Service Bulletin No. 787B, dated August 25, 1993. 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 Piper Aircraft Corporation, 2926 Piper Drive, Vero Beach, Florida 32960. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief 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.

(f) This amendment becomes effective on August 12, 1994.

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 PA34-200, PA34-200T, PA34-220T, PA44-180, and PA44-180T airplanes was published in the Federal Register on January 12, 1994 (59 FR 1676). The action proposed to require repetitively inspecting the MLG trunnions for cracks, replacing any trunnions found cracked, and eventually replacing these trunnions with improved parts as terminating action for the repetitive inspection requirement. The proposed inspections would be accomplished in accordance with Piper Service Bulletin (SB) No. 787B, dated August 25, 1993. The proposed replacement would be accomplished in accordance with the applicable maintenance manual.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the four comments received.

One commenter states that, with the waythe compliance of paragraph (b) of the proposal is currently written, airplanes with trunnions that have over 2,000 hours time-in-service (TIS) are grounded. The commenter requests that the FAA give airplane operators in this scenario a grace period. The FAA concurs and has changed the compliance portion of paragraph (b) of the AD to: "Upon the accumulation of 2,000 hours TIS on a MLG trunnion or within the next 100 hours TIS, whichever occurs later, . . . ". This change would give 100 hours TIS for compliance to those operators with 1,901 hours TIS or more accumulated on a trunnion as of the effective date of the AD.

This same commenter also states that, in paragraph (b)(1) of the proposal, an affected airplane could be grounded if parts were not available after 2,500 hours TIS (2,000 hours TIS replacement compliance and 500 hours TIS for parts unavailability grace period). This commenter recommends that, if parts are unavailable, the FAA allow the owner/operator to inspect the airplane every 100 hours TIS until parts are available and not just for the next 500 hours TIS. The FAA concurs that airplanes would be grounded at 2,500 hours TIS if parts were not available. However, the Piper Aircraft Corporation has assured the FAA that an adequate surplus of parts currently exist for all operators to comply with this action. The AD is unchanged as a result of this comment.

One commenter recommends that, instead of mandatory replacement, the FAA mandate the 100-hour TIS repetitive inspections with mandatory replacement of trunnions found cracked. The FAA does not concur. The FAA analyzed information related to MLG trunnion failures from service difficulty reports and manufacturer's warranty claims; and, from this information, the FAA established the mandatory replacement in order to maintain these airplanes at their original type certification level of safety. The AD is unchanged as a result of this comment.

Another commenter feels that an eddy current inspection of the MLG trunnions is more reliable than the dye penetrant inspections. This commenter states that, based upon similar MLG trunnion failures in the United Kingdom, the dye penetrant inspection method may not detect a critical crack. The FAA does not concur. Past experience based on FAA reports indicates that dye penetrant inspections are very successful in detecting cracks in the MLG trunnions, and the equipment needed is more readily available and less costly than that for eddy current inspections. The FAA will consider any requests to accomplish an eddy current inspections as an alternative method of compliance to paragraph (a) of the AD under provisions specified in paragraph (d) of the AD. The AD is unchanged as a result of this comment.

This same commenter addresses lateral grinding marks found on a significant number of MLG trunnions in the area of the past crack initiation. This commenter recommends blending these marks out to remove any traces of scoring. The FAA concurs, and has added provisions for this requirement to the AD.

A commenter recommends that this AD action also cover inspections in two other locations in the MLG, the swivel pin and trunnion attach fittings. The FAA issued an advanced notice of proposed rulemaking (ANPRM) on February 11, 1994, to seek comments regarding the best action (if any) to take in order to correct any possible problems with retractable MLG swivel pins. The FAA is currently reviewing comments from this ANPRM and has not determined that there is an unsafe condition that requires AD action under part 39 of the Federal Aviation Regulations (14 CFR part 39). The MLG trunnion attach fittings are the subject of Piper SB No. 956, dated March 3, 1992. The FAA has evaluated all information related to this issue and has determined that AD action is not justified at this point. The FAA will continue to evaluate any additional information, and, if necessary, will implement future rulemaking. TheAD is unchanged as a result of this comment.

The manufacturer has informed the FAA that certain Piper Model PA34-220T airplanes (serial numbers 34-8133001 through 34-8233088) may be equipped with trunnion housing assemblies, Piper part number 39486-802 (left) and 39486-803 (right) with embossed forging number 67924-2. The FAA has determined that this AD should not apply to airplanes with these trunnion housing assemblies installed. The FAA has revised the Applicability section of the final rule to reflect this change.

No comments were received on the FAA's determination of the cost impact of this proposed action upon U.S. operators of the affected airplanes.

After careful review of all available information, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for the compliance time change in paragraph (b) of the proposal, the Applicability section change, the addition of the provision to blend any lateral grinding marks, and minor editorial corrections. The FAA has determined that these changes, the addition, and any editorial corrections will not change the meaning of the AD nor add any additional burden upon the public than was already proposed.

The FAA estimates that 2,265 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 16 workhours per airplane to accomplish the required action, and that the average labor rate is approximately $55 an hour. Parts cost approximately $1,100 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $4,484,700. This figure is based on the assumption that no affected airplane owner/operator has accomplished the required action. The FAA believes that some airplanes owners have already accomplished the required actions. With this in mind, the FAA anticipates that the cost of this AD will be much lower than the figure referenced above.

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 atthe 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by adding a new AD to read as follows: