Airworthiness Directives; Bell Helicopter Textron, Inc. Model 204B, 205A, 205A-1, 205B, 212, and 412 Helicopters

SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to Bell Helicopter Textron, Inc. (BHTI) Model 205B,

212, and 412 helicopters, that currently requires a repetitive magnetic

particle inspection of the main transmission lower planetary spider.

This amendment expands the applicability to include the BHTI Model

204B, 205A, and 205A-1 helicopters. This amendment is prompted by the

need to apply the magnetic particle inspections required by that AD to

additional BHTI model helicopters, as well as more clearly state the

applicable compliance times for these inspections. The actions

specified by this AD are intended to prevent a fatigue failure of the

main transmission lower planetary spider, which could result in failure

of the main transmission, and subsequent loss of control of the

helicopter.

EFFECTIVE DATE: July 29, 1994.

ADDRESSES: This AD and any related information may be examined in the

Rules Docket at the Federal Aviation Administration, Office of the

Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth,

Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Uday Garadi, Aerospace Engineer,

Rotorcraft Directorate, Rotorcraft Certification Office, ASW-170, 2601

Meacham Boulevard, Fort Worth, Texas 76193-0170, telephone (817) 222-

5157, fax (817) 222-5959.

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

Aviation Regulations by superseding AD 92-11-07, Amendment 39-8257 (57

FR 30392, July 9, 1992), which is applicable to Bell Helicopter

Textron, Inc. (BHTI) Model 205B, 212, and 412 helicopters, was

published in the Federal Register on March 23, 1993 (58 FR 15444). That

action proposed to apply the current requirements for a repetitive

magnetic particle inspection (MPI) of the main transmission lower

planetary spider (spider), part number (P/N) 204-040-785-003, to BHTI

Model 204B, 205A, and 205A-1 helicopters.

Interested persons have been afforded an opportunity to participate

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

the comments received.

One comment was received. The commenter states that a 3,100 hours'

time-in-service MPI interval is redundant for the Model 204B since an

MPI is required at overhaul. The FAA does not agree. An MPI is not

required at overhaul for all operators. The manufacturer's overhaul

time and associated inspection requirements are mandatory only for

those operators whose maintenance program is based on the BHTI program.

Therefore, this is not a redundant requirement for those operators who

do not perform their overhauls in accordance with the manufacturer's

suggestions.

The same commenter states that BHTI Models 204B and 205A-1 should

not be included in the AD because the torque applied to the spider when

installed in the Models 204B and 205A-1 is lower than when the spider

is installed in the Models 212 and 412. The FAA does not concur with

this comment. Since parts can be swapped from Models 212 and 412 with

higher torque or power requirements to the Models 204B and 205A-1 with

lower torque requirements, the FAA concludes that the required MPI is

essential for safety.

This commenter also states that the Models 205A and 205A-1 have

different transmission overhaul intervals than the Model 212 and 412

helicopters and indicates that this AD inspection interval should

consider these different overhaul intervals. The FAA has considered

this in arriving at the MPI inspection interval. The MPI interval of

3,100 hours' time-in-service is based on the amount of time it takes a

crack to propagate from initiation to failure under typical flight

conditions and is also compatible with typical overhaul intervals. The

MPI interval of 3,100 hours' time-in-service will provide for crack

detection before failure without imposing an undue burden on operators.

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, except for

editorial and address changes. The FAA has determined that these

changes will neither increase the economic burden on any operator nor

increase the scope of the AD.

The FAA estimates that 1,207 helicopters of U.S. registry will be

affected by this AD, that it will take approximately 6 work hours per

helicopter if performed during transmission overhaul, or 32 work hours

if not performed during overhaul, to accomplish the required actions,

and that the average labor rate is $55 per work hour. It is estimated

that one-half of the affected helicopter fleet may be affected each

year by the requirements of this AD. Based on these figures, the total

cost impact of the AD on U.S. operators is estimated to range from

$199,155 to $1,062,160.

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, 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-8257 (57 FR

30392, July 9, 1992) and by adding a new airworthiness directive (AD),

Amendment 39-8683, to read as follows:

AD 93-17-12 Bell Helicopter Textron, Inc. (BHTI): Amendment 39-8683.

Docket No. 92-ASW-49. Supersedes AD 92-11-07, Amendment 39-8257.

Applicability: Model 204B, 205A, 205A-1, 205B, 212, and 412

helicopters, with main rotor transmission lower planetary spider

(spider), part number (P/N) 204-040-785-003, installed, certificated

in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent fatigue failure of the spider, which could result in

failure of the main transmission and subsequent loss of control of

the helicopter, accomplish the following:

(a) Within the next 600 hours' time-in-service (TIS) after the

effective date of this AD, unless previously accomplished within the

last 2,500 hours' TIS, and thereafter at intervals not to exceed

3,100 hours' TIS from the last magnetic particle inspection (MPI),

remove the spider and perform an MPI for cracks in accordance with

the pertinent BHTI maintenance, repair, and overhaul manuals.

(b) Replace any cracked spider with an airworthy part prior to

further flight.

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

compliance time that provides an acceptable level of safety may be

used when approved by the Manager, Rotorcraft Certification Office,

FAA, Rotorcraft Directorate. Operators shall submit their requests

through an FAA Principal Maintenance Inspector, who may concur or

comment and then send it to the Manager, Rotorcraft Certification

Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Manager, Rotorcraft Certification Office.

(d) 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 helicopter to a location where

the requirements of this AD can be accomplished.

(e) This amendment becomes effective on July 29, 1994.

Issued in Fort Worth, Texas, on May 13, 1994.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 94-15408 Filed 6-23-94; 8:45 am]

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