Airworthiness Directives; Teledyne Continental Motors IO-346, IO- 520, and IO-550 Series Piston Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 92-ANE-50; Amendment 39-8896; AD 94-09-07]

Airworthiness Directives; Teledyne Continental Motors IO-346, IO-

520, and IO-550 Series Piston Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Teledyne Continental Motors (TCM) IO-346, IO-520,

and IO-550 series piston engines, that requires initial and repetitive

inspections of the engine mount brackets for cracks, and if found

cracked, replacement with improved design engine mount brackets. All

engine mount brackets require replacement with improved design engine

mount brackets at the next engine removal after the effective date of

this AD. This amendment is prompted by reports of cracks in engine

mount brackets on engines that have completed at least one overhaul

cycle. The actions specified by this AD are intended to prevent engine

separation from the aircraft due to cracks in the engine mount

brackets.

DATES: Effective July 5, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of July 5, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Teledyne Continental Motors, P.O. Box 90, Mobile, AL

36601; telephone (205) 438-3411. This information may be examined at

the Federal Aviation Administration (FAA), New England Region, Office

of the Assistant Chief Counsel, 12 New England Executive Park,

Burlington, MA; or at the Office of the Federal Register, 800 North

Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Jerry Robinette, Aerospace Engineer,

Atlanta Aircraft Certification Office, FAA, Small Airplane Directorate,

1669 Phoenix Parkway, suite 210C, Atlanta, GA 30349; telephone (404)

991-3810, fax (404) 991-3606.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to Teledyne Continental Motors (TCM) IO-346, IO-520, and IO-

550 series piston engines was published in the Federal Register on

October 20, 1993 (58 FR 54072). That action proposed to require initial

and repetitive dye penetrant inspections for cracks in certain lower

left engine mount brackets, Part Number (P/N) 630695. If the lower left

engine mount bracket is found cracked, that proposed rule would require

replacing both the lower left and lower right engine mount brackets

with improved design engine mount brackets, P/N 653306 and 653305,

respectively. If a crack is not detected, the lower left engine mount

bracket would require repetitive inspections at intervals not to exceed

500 hours time in service (TIS) until the next engine removal, at which

time engine mount brackets, P/N 630694 and 630695, would be replaced

with improved design engine mount brackets, P/N 653306 and 653305.

Installation of these improved design engine mount brackets would

constitute terminating action to the inspection requirements of that

AD. The actions would be required to be accomplished in accordance with

TCM Service Bulletin (SB) No. M92-13, dated September 4, 1992.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the one comment received.

The commenter supports the proposed rule but states that the

interval for the repetitive inspections should be reduced from 500

hours TIS to 100 hours TIS. The commenter states that if the bracket is

found broken, the airframe engine mount and surrounding areas should be

inspected for damage and the upper brackets and all bolts and nuts

should be replaced as they may be overstressed. The commenter further

states that the pilot should visually inspect the brackets on each

preflight.

The FAA does not concur with the recommendation to reduce the

repetitive inspection interval to 100 hours TIS. Data provided from the

manufacturer indicates that the repetitive inspection interval of 500

hours TIS is sufficient once the initial inspection is satisfactorily

completed.

The FAA does not concur with the commenter's recommendation to

inspect the airframe engine mount and surrounding areas for damage and

to replace all bolts and nuts if the bottom brackets are found broken.

Once the bottom brackets are broken, there is essentially no load being

transmitted to the lower airframe structure. In addition, a structural

analysis of the bolt strength indicates that with only the two upper

mounts securing the engine, safety factors exceed required values for

normal category ``g'' loading. Therefore, none of the bolts and nuts

should be overstressed.

The FAA does not concur with the commenter's recommendation to

require the pilot to visually inspect the brackets on each preflight.

Based on the data presented above, the FAA has determined that it is

not necessary to inspect the brackets on each preflight.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule as proposed.

There are approximately 9,750 TCM IO-346, IO-520, and IO-550 series

piston engines of the affected design in the worldwide fleet. The FAA

estimates that 8,300 engines installed on aircraft of U.S. registry

will be affected by this AD, that it will take approximately 2 work

hours per inspection, and if the engine mount brackets must be

replaced, an additional 4 work hours will be required. The average

labor rate is $55 per work hour. Required parts will cost approximately

$320 per engine. Based on these figures, the total cost impact of the

AD on U.S. operators is estimated to be $5,395,000.

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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from 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 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

airworthiness directive:

94-09-07 Teledyne Continental Motors: Amendment 39-8896. Docket 92-

ANE-50.

Applicability: Teledyne Continental Motors (TCM) engine models

IO-346A, IO-346B, IO-520C, IO-520CB, and IO-550C; rebuilt engine

model IO-520C with serial numbers (S/N) 287051-R and lower; rebuilt

engine model IO-520CB with S/N 282226-R and lower; rebuilt engine

model IO-550C with S/N 271742-R and lower; and all factory

overhauled IO-520C, IO-520CB, and IO-550C engines with a build date

prior to August 6, 1992. These engines are installed on but not

limited to Beech model A23, A23A, 95-C55, 95-C55A, D55, D55A, E55,

E55A, 58, and 58A airplanes.

Compliance: Required as indicated, unless accomplished

previously.

To prevent engine separation from the aircraft due to cracks in

the engine mount brackets, accomplish the following:

(a) For engines with engine mount brackets that have completed

at least one engine overhaul cycle, or have accumulated 2,500 or

more hours time in service (TIS) on the effective date of this AD,

inspect the lower left engine mount bracket, Part Number (P/N)

630695, for cracks using the dye penetrant techniques specified in

this paragraph and in accordance with TCM Service Bulletin (SB) No.

M92-13, dated September 4, 1992, within the next 50 hours TIS after

the effective date of this AD.

(1) Perform the dye penetrant inspection as follows:

Note: Military Specification MIL-I-6866 and American Society of

Testing Materials specifications ASTM E1417-93 and E165-9 contain

additional information on dye penetrant inspection processes.

(i) Preparation: clean and dry all parts in such a manner as to

leave the surfaces free from grease, oil, soaps, alkalies, and other

substances which would interfere with inspection. Vapor degreasing

is generally suitable for this purpose.

(ii) Penetrant Application Procedure: after preparation, spray

or brush the parts with the penetrant, and allow to stand for not

less than 5 minutes. The effectiveness of the penetrant increases if

left standing for a longer time, as the penetrant will reach finer

discontinuities.

(iii) Penetrant Cleaning: clean the parts thoroughly using a

medium which will remove penetrant from the surfaces of parts; wash

with water when the penetrant is water soluble. When other than

water soluble penetrants are used, the penetrant shall be removed

with a suitable cleaner. Avoid excessive cleaning which would remove

the penetrant from discontinuities.

(iv) Drying: dry the parts as thoroughly as possible. Drying of

parts may be accomplished by evaporation at room temperature or by

placing the parts in a circulating warm air oven or in the air

stream of a hot air dryer. Avoid excessive drying time or drying

temperatures above 75 deg.C (165 deg.F) to prevent excessive

evaporation of the penetrant. If heat is used for drying parts, cool

parts to approximately 50 deg.C (120 deg.F) before proceeding to the

developing procedure.

(v) Developing: apply the developer to the dry parts as lightly

and as evenly as possible, using as thin a coating of developer as

is possible. A translucent film is adequate. Mix wet developer by

agitation immediately prior to applying it. After applying the

developer, take care that no penetrant indication is disturbed or

obliterated in subsequent handling.

(vi) Examination: examine the developed penetrant indications in

accordance with the dye penetrant manufacturer's instructions.

Examine parts for indications of discontinuities open to the

surface.

(vii) Final cleaning: clean the parts following the inspection

to remove penetrant and developer.

Note 1: Caution: Because of differences among penetrants, take

care to ensure that the final cleaner, the penetrant, the penetrant

remover, and the developer are suitable for use with each other.

Note 2: Caution: All penetrant materials should be kept as free

from moisture as possible.

Note 3: Caution: Most penetrants, cleaning agents, and developer

suspensions are low flash point material; use caution to prevent

fires.

(2) If no crack is detected, inspect in accordance with

paragraph (a) of this AD at intervals not to exceed 500 hours TIS

since the last inspection.

(3) If a crack is detected, prior to further flight replace both

the lower left engine mount bracket, P/N 630695, and lower right

engine mount bracket, P/N 630694, with improved design engine mount

brackets, P/N 653306 and 653305, respectively.

(b) For all engines, replace both the lower left engine mount

bracket, P/N 630695, and lower right engine mount bracket, P/N

630694, with improved design engine mount brackets, P/N 653306 and

653305, respectively, at the next engine removal after the effective

date of this AD.

(c) Installation of the improved design engine mount brackets,

P/N 653306 and 653305, constitutes terminating action to the

inspection requirements of this AD.

(d) An alternative method of compliance or adjustment of the

compliance time that provides an acceptable level of safety may be

used if approved by the Manager, Atlanta Aircraft Certification

Office. The request should be forwarded through an appropriate FAA

Maintenance Inspector, who may add comments and then send it to the

Manager, Atlanta Aircraft Certification Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Atlanta Aircraft Certification

Office.

(e) Special flight permits may be issued in accordance with 14

CFR 21.197 and 21.199 to operate the aircraft to a location where

the requirements of this AD can be accomplished.

(f) The inspection and replacement shall be done in accordance

with the following service bulletin:

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Document No. Pages Revision Date

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TCM SB M92-13....................................... 1-2 Original............ Sept. 4, 1992.

Total Pages: 2.

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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 Teledyne Continental Motors, P.O.

Box 90, Mobile, AL 36601; telephone (205) 438-3411. Copies may be

inspected at the FAA, New England Region, Office of the Assistant

Chief Counsel, 12 New England Executive Park, Burlington, MA; or at

the Office of the Federal Register, 800 North Capitol Street NW.,

suite 700, Washington, DC.

(g) This amendment becomes effective on July 5, 1994.

Issued in Burlington, Massachusetts, on April 19, 1994.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 94-10500 Filed 5-4-94; 8:45 am]

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