Airworthiness Directives; Teledyne Continental Motors (formerly Bendix) S-20, S-1200, D-2000, and D-3000 Series Magnetos

SUMMARY: This notice revises an earlier proposed airworthiness

directive (AD), applicable to Teledyne Continental Motors (TCM)

(formerly Bendix) S-20, S-1200, D-2000, and D-3000 series magnetos

equipped with impulse couplings, that would have superseded an AD that

currently requires inspections for wear, and replacement, if necessary,

of the impulse coupling assemblies. The proposed rule would have

retained the repetitive inspections for wear required by the current

AD, but would have also required replacement, if necessary, of riveted

impulse coupling assemblies with newly designed, improved, snap ring

impulse coupling assemblies. In addition, the proposed AD would have

required marking the magneto data plate to indicate installation of a

snap ring impulse coupling assembly. Installation of snap ring impulse

coupling assemblies would have constituted terminating action to the

inspection requirements of the AD. That proposal was prompted by

availability of an improved design for the impulse coupling assembly.

This action revises the proposed rule by retaining the 500 hour

repetitive inspections for wear required by the current AD but makes

them effective for the snap ring couplings as well. The actions

specified by this proposed AD are intended to prevent magneto failure

and subsequent engine failure.

DATES: Comments must be received by January 17, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), New England Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 93-ANE-07, 12 New England

Executive Park, Burlington, MA 01803-5299. Comments may be inspected at

this location between 8:00 a.m. and 4:30 p.m., Monday through Friday,

except Federal holidays.

The service information referenced in the proposed rule 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 FAA, New England Region, Office of the Assistant Chief Counsel, 12

New England Executive Park, Burlington, MA.

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:

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 summarizing 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 Number 93-ANE-07.'' 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, New England Region, Office of the Assistant Chief Counsel,

Attention: Rules Docket No. 93-ANE-07, 12 New England Executive Park,

Burlington, MA 01803-5299.

Discussion

On January 4, 1983, the Federal Aviation Administration (FAA)

issued airworthiness directive (AD) 78-09-07 R3, Amendment 39-4538 (48

FR 1482, January 13, 1983), to require inspections for wear, and

replacement, if necessary, of the impulse coupling assemblies on

certain Teledyne Continental Motors (TCM) (formerly Bendix) S-20, S-

1200, D-2000, and D-3000 series magnetos equipped with impulse

couplings. That action was prompted by reports of numerous magneto

failures. That condition, if not corrected, could result in magneto

failure and subsequent engine failure.

A proposal to amend part 39 of the Federal Aviation Regulations was

published as a notice of proposed rulemaking (NPRM) in the Federal

Register on September 21, 1993 (58 FR 48987). That NPRM would have

retained the repetitive inspections for wear required by the current

AD, but would have also required replacement, if necessary, of the

riveted impulse coupling assembly with newly designed, improved, snap

ring impulse coupling assemblies. In addition, the proposed AD would

have required marking the magneto data plate to indicate installation

of a snap ring impulse coupling assembly. Installation of snap ring

impulse coupling assemblies would have constituted terminating action

to the inspection requirements of this AD. That NPRM was prompted by

the manufacturer redesigning the impulse coupling assembly to include

snap ring fastening technology which strengthens the cam axle and

reduces wear. The snap ring impulse coupling assembly was believed not

to have the failure mode of the previous design.

Since the issuance of that NPRM, the FAA has received reports of

snap ring impulse coupling assemblies being worn beyond limits. This

supplemental proposed AD would therefore retain the 500 hour repetitive

inspections for wear required by the current AD, but would require

these inspections for magnetos equipped with snap ring impulse coupling

assemblies as well. Since this change expands the scope of the

originally proposed rule, the FAA has determined that it is necessary

to reopen the comment period to provide additional opportunity for

public comment.

The FAA has reviewed and approved the technical contents of TCM

Mandatory Service Bulletin (MSB) No. MSB645, dated April 4, 1994, that

describes procedures for inspection of the impulse coupling assemblies

for wear; and TCM SB No. 639, dated March 1993, that clarifies

procedures for installation of impulse coupling assemblies.

The FAA estimates that 130,000 magnetos would be affected by this

proposed AD, that the required inspection would take 1 work hour, plus

1 work hour to change the impulse coupling, and that the average labor

rate is $55 per work hour. The average utilization of the fleet of

these airplanes is estimated to be evenly divided between commercial/

commuter service and private owners. The commercial/commuter service

population is estimated to operate 500 hours time in service (TIS) per

year; therefore the cost to perform the inspections required by the

proposed AD would be approximately $3,575,000 per year. The FAA

estimates that private owners operate their aircraft between 50 and 100

hours TIS per year; therefore it will take approximately 5 to 10 years

to reach 500 hours time in service. The estimated cost for these owners

would also be $3,575,000 spread over a time period of 5 to 10 years or

715,000 per year for 5 years or $357,500 for 10 years. The cost to

replace the impulse coupling assembly is $125 per magneto plus one work

hour at $55 per work hour for a total of $180 per magneto. While all

the riveted impulse coupling assemblies will eventually have to be

replaced, it is not possible to estimate the cost per year. The total

cost for replacement for U.S. operators would be $23,400,000.

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 proposed

regulation (1) is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the 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 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, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend

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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Teledyne Continental Motors: Docket No. 93-ANE-07.

Applicability: Teledyne Continental Motors (TCM) (formerly

Bendix) S-20, S-1200, D-2000, and D-3000 series magnetos equipped

with impulse couplings, installed on but not limited to

reciprocating engine powered aircraft manufactured by Beech, Cessna,

Mooney, and Piper.

Note: The Federal Aviation Administration (FAA) has received

reports of some confusion as to what is meant by S-20, S-1200, D-

2000, and D-3000 series magnetos as referenced in TCM Mandatory

Service Bulletin (MSB) No. MSB645, dated April 4, 1994, and this

airworthiness directive (AD). A typical example is S6RN-25, where

the S designates single type ignition unit (a D designates a dual

ignition unit), the 6 designates the number of cylinders, the R

designates right hand rotation, the N is the manufacturer

designation (this did not change when TCM purchased the Bendix

magneto product line), and the number after the dash indicates the

series (a-25 is a S-20 series magneto while a-3200 is a D-3000

series magneto, etc.).

Compliance: Required as indicated, unless accomplished

previously.

To prevent magneto failure and subsequent engine failure,

accomplish the following:

(a) For magnetos with riveted or snap ring impulse coupling

assemblies, having less than 450 hours time in service (TIS) since

new, or overhaul, or since last inspection, on the effective date of

this AD, accomplish the following:

(1) Prior to the accumulation of 500 hours TIS since new, or

overhaul, or since last inspection, inspect riveted or snap ring

impulse coupling assemblies for wear, and replace, if necessary,

prior to further flight, with serviceable snap ring impulse coupling

assemblies, in accordance with the Detailed Instructions of TCM MSB

No. MSB645, dated April 4, 1994, and TCM SB No. 639, dated March

1993.

(2) Thereafter, at intervals not to exceed 500 hours TIS since

the last inspection, inspect riveted or snap ring impulse coupling

assemblies for wear, and replace, if necessary, prior to further

flight, with serviceable snap ring impulse coupling assemblies, in

accordance with the Detailed Instructions of TCM MSB No. MSB645,

dated April 4, 1994, and TCM SB No. 639, dated March 1993.

(b) For magnetos with riveted or snap ring impulse coupling

assemblies, having 450 or more hours TIS since new, or overhaul, or

since last inspection, on the effective date of this AD, or an

unknown TIS on the effective date of this AD, accomplish the

following:

(1) Within the next 50 hours TIS after the effective date of

this AD, inspect riveted or snap ring impulse coupling assemblies

for wear, and replace, if necessary, prior to further flight, with

serviceable snap ring impulse coupling assemblies in accordance with

the Detailed Instructions of TCM MSB No. MSB645, dated April 4,

1994, and TCM SB No. 639, dated March 1993.

(2) Thereafter, at intervals not to exceed 500 hours TIS since

the last inspection, inspect riveted or snap ring impulse coupling

assemblies for wear, and replace, if necessary, prior to further

flight, with serviceable snap ring impulse coupling assemblies, in

accordance with the Detailed Instruction of TCM MSB No. MSB645,

dated April 4, 1994, and TCM SB No. 639, dated March 1993.

(c) 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.

(d) Special flight permits may be issued in accordance with

Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR

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

requirements of this AD can be accomplished.

Issued in Burlington, Massachusetts, on November 9, 1994.

James C. Jones,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-28375 Filed 11-16-94; 8:45 am]

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