Airworthiness Directives: Piper Aircraft Corporation Models PA34- 200, PA34-200T, PA34-220T, PA44-180, and PA44-180T Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-CE-58-AD]

Airworthiness Directives: Piper Aircraft Corporation Models PA34-

200, PA34-200T, PA34-220T, PA44-180, and PA44-180T Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to adopt a new airworthiness directive

(AD) that would apply to certain Piper Aircraft Corporation (Piper)

Models PA34-200, PA34-200T, PA34-220T, PA44-180, and PA44-180T

airplanes. The proposed action would require repetitively inspecting

the main landing gear trunnions for cracks, replacing any trunnions

found cracked, and eventually replacing the landing gear trunnions with

parts of improved design as terminating action for the repetitive

inspection requirement. Several reports of the main landing gear

trunnions cracking on the affected airplanes prompted the proposed

action. The actions specified by the proposed AD are intended to

prevent collapse of the main landing gear caused by cracked trunnions,

which could result in airplane damage.

DATES: Comments must be received on or before March 14, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Central Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 93-CE-58-AD, room 1558, 601 E.

12th Street, Kansas City, Missouri 64106. Comments may be inspected at

this location between 8 a.m. and 4 p.m., Monday through Friday,

holidays excepted.

Service information that applies to the proposed AD may be obtained

from the Piper Aircraft Corporation, Customer Services, 2926 Piper

Drive, Vero Beach, Florida 32960. This information also may be examined

at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT: Christina Marsh, Aerospace Engineer,

FAA, Atlanta Aircraft Certification Office, 1669 Phoenix Parkway, suite

210C, Atlanta, Georgia 30349; telephone (404) 991-2910; facsimile (404)

991-3606.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed rule by submitting such written data, views, or arguments as

they may desire. Communications should identify the Rules Docket number

and be submitted in triplicate to the address specified above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed rule. All

comments submitted will be available, both before and after the closing

date for comments, in the Rules Docket for examination by interested

persons. A report that summarizes each FAA-public contact concerned

with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 93-CE-58-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Central Region, Office of the Assistant Chief Counsel,

Attention: Rules Docket No. 93-CE-58-AD, room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Discussion

Service history of certain Piper Models PA34-200, PA34-200T, PA34-

220T, PA44-180, and PA44-180T airplanes reveals several occurrences of

cracked main landing gear (MLG) trunnions. Five of these occurrences

resulted when the left MLG trunnion, part number (P/N) 67926-12,

separated from Piper Model PA34-200T airplanes during the landing roll.

Further investigation revealed that the left MLG collapsed because of a

transverse fracture in the trunnion at the rear web lower end fillet.

Metallurgical examination of four of these MLG trunnions further

disclosed that the fractures originated from very shallow fatigue

cracks originating from several areas along the rear surface at the

lower end of the fillet web. The length of these fatigue cracks ranged

from .20 to .40 inches.

Piper has issued Service Bulletin (SB) 787B, dated August 25, 1993,

which specifies procedures for inspecting the MLG trunnions on certain

Piper Models PA34-200, PA34-200T, PA34-220T, PA44-180, and PA44-180T

airplanes, and references replacing MLG trunnions with parts of

improved design.

After examining the circumstances and reviewing all available

information related to the incidents described above including the

referenced service information, the FAA has determined that AD action

should be taken to prevent collapse of the main landing gear caused by

cracked trunnions, which could result in airplane damage.

Since an unsafe condition has been identified that is likely to

exist or develop in other Piper Models PA34-200, PA34-200T, PA34-220T,

PA44-180, and PA44-180T airplanes of the same type design, the proposed

AD would require repetitively inspecting the main landing gear

trunnions for cracks, replacing any trunnions found cracked, and

eventually replacing the landing gear trunnions with parts of improved

design as terminating action for the repetitive inspection requirement.

The proposed inspections would be accomplished in accordance with Piper

SB No. 787B, dated August 25, 1993. The proposed replacement would be

accomplished in accordance with the applicable maintenance manual.

The FAA estimates that 2,265 airplanes in the U.S. registry would

be affected by the proposed AD, that it would take approximately 16

workhours per airplane to accomplish the proposed initial inspection

and replacement, 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 proposed AD on U.S. operators is

estimated to be $4,484,700. This cost figure is based on the assumption

that none of the affected airplane owners/operators have accomplished

the proposed actions. The FAA believes that some airplane owners/

operators have already incorporated the inspection terminating MLG

trunnion replacements. With this in mind, the FAA anticipates that the

cost of the proposed AD would be much lower than the figure referenced

above.

The regulations proposed herein would 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

proposal would 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) if promulgated,

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 draft regulatory evaluation

prepared for this action has been placed 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, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend 14

CFR part 39 of the Federal Aviation Regulations 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new AD:

Piper Aircraft Corporation: Docket 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

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) 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) 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.

(2) 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.

(3) If one trunnion is found cracked and is replaced as

specified in paragraph (a)(1) of this AD, the other trunnion must

still be reinspected as specified in paragraph (a)(2) of this AD

until it also is replaced.

(b) Upon the accumulation of 2,000 hours TIS on a MLG trunnion,

unless already accomplished as specified in paragraph (a)(1) of this

AD, replace this 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 Service Bulletin (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.

(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 FAR

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) All persons affected by this directive may obtain copies of

the document referred to herein upon request to the Piper Aircraft

Corporation, 2926 Piper Drive, Vero Beach, Florida 32960; or may

examine this document at the FAA, Central Region, Office of the

Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City,

Missouri 64106.

Issued in Kansas City, Missouri, on January 5, 1994.

Barry D. Clements,

Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 94-700 Filed 01-11-94; 8:45 am]

BILLING CODE 4910-13-U