Airworthiness Directives; Bell Helicopter Textron, Inc. Model 214ST Helicopters

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-SW-25-AD]

Airworthiness Directives; Bell Helicopter Textron, Inc. Model

214ST Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness

[[Page 58357]]

directive (AD), applicable to Bell Helicopter Textron, Inc. (BHTI)

Model 214ST helicopters, that currently establishes a mandatory

retirement life of 50,000 high-power events for the main rotor mast

(mast). This action would require changing the retirement life for the

mast from high-power events to a maximum accumulated Retirement Index

Number (RIN) of 140,000 and apply this RIN to an additional part

numbered mast. This proposal is prompted by fatigue analyses and tests

that show certain masts fail sooner than originally anticipated because

of an unanticipated high number of takeoffs and external load lifts in

addition to the deterioration in strength that occurs under other

operating conditions. The actions specified by the proposed AD are

intended to prevent fatigue failure of the mast, which could result in

failure of the main rotor system and subsequent loss of control of the

helicopter.

DATES: Comments must be received by January 13, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of the Assistant Chief Counsel, Attention:

Rules Docket No. 94-SW-25-AD, 2601 Meacham Blvd., Room 663, Fort Worth,

Texas 76137. Comments may be inspected at this location between 9:00

a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be

obtained from Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth,

Texas 76101.

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

FAA, Rotorcraft Certification Office, Rotorcraft Directorate, Fort

Worth, Texas 76193-0170, telephone (817) 222-5157, fax (817) 222-5959.

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 No. 94-SW-25-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, Office of the Assistant Chief Counsel, Attention: Rules

Docket No. 94-SW-25-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas

76137.

Discussion

On July 13, 1994, the FAA issued AD 94-15-04, Amendment 39-8975,

(59 FR 37155, July 21, 1994), to require changing the method of

calculating the retirement life for the mast, part number (P/N) 214-

040-090-109, from flight hours to high-power events calculated using

the number of takeoffs and external load lifts (torque events). That

action was prompted by fatigue analysis and retesting that showed

certain masts fail sooner than originally anticipated because of an

unanticipated high number of takeoffs and external load lifts performed

with those masts in addition to the anticipated deterioration in

strength that occurs under other operating conditions. The requirements

of that AD are intended to prevent fatigue failure of the mast, which

could result in failure of the main rotor system and subsequent loss of

control of the helicopter.

Since the issuance of that AD, BHTI has issued BHTI Information

Letter GEN-94-54, dated April 15, 1994, Subject: Retirement Index

Number (RIN) For Cycle Lifed Components, which introduces a different

method of accounting for fatigue damage on components that have

shortened service lives as a result of frequent torque events.

Additionally, BHTI has issued BHTI Alert Service Bulletin (ASB) 214ST-

94-67, dated November 7, 1994, which is applicable to Model 214ST

helicopters, which describes procedures for creation of a component

history card within the next 25 hours time-in-service (TIS) for the

Model 214ST helicopters. The ASB also describes an alternate retirement

life of a maximum RIN count of 140,000 for the Model 214ST mast.

Finally, the ASB includes an additional P/N for the main rotor mast

which was not included in the existing AD.

Since an unsafe condition has been identified that is likely to

exist or develop on other BHTI Model 214ST helicopters of the same type

design, the proposed AD would supersede AD 94-15-04 to require creation

of a component history card using RIN counts, and establish a

retirement life of a maximum accumulated RIN for the masts of 140,000.

The FAA estimates that nine helicopters of U.S. registry would be

affected by this proposed AD, that it would take approximately (1) 48

work hours per helicopter to replace the mast; (2) 2 work hours per

helicopter to create the component history card or equivalent record

(record); and (3) 10 work hours per helicopter to maintain the record

each year, and that the average labor rate is $60 per work hour.

Required parts would cost approximately $17,267 per mast. Based on

these figures, the total cost impact of the proposed AD on U.S.

operators is estimated to be $36,700 for the first year and $35,800 for

each subsequent year. These costs assume replacement of the mast in

one-sixth of the fleet each year, creation and maintenance of the

records for all the fleet the first year, and creation of one-sixth of

the fleet's records and maintenance of the records for all the fleet

each subsequent year.

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.

[[Page 58358]]

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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-8975 (59 FR

37155, July 21, 1994), and by adding a new airworthiness directive

(AD), to read as follows:

Bell Helicopter Textron, Inc. (BHTI): Docket No. 94-SW-25AD.

Supersedes AD 94-15-04, Amendment 39-8975.

Applicability: Model 214ST helicopter with main rotor mast

(mast), part number (P/N) 214-040-090-109 or P/N 214-040-090-121,

installed, certificated in any category.

Note 1: This AD applies to each helicopter identified in the

preceding applicability provision, regardless of whether it has been

modified, altered, or repaired in the area subject to the

requirements of this AD. For helicopters that have been modified,

altered, or repaired so that the performance of the requirements of

this AD is affected, the owner/operator must use the authority

provided in paragraph (e) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition, or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any helicopter from the applicability of this AD.

Compliance: Required within 25 hours time-in-service (TIS) after

the effective date of this AD, unless accomplished previously.

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

failure of the main rotor system and subsequent loss of control of

the helicopter, accomplish the following:

(a) Create a component history card or an equivalent record for

the affected mast.

(b) Determine and record the accumulated Retirement Index Number

(RIN) to date on the mast as follows:

(1) For operators with mast, P/N 214-040-090-109, multiply the

takeoffs and external load lifts (high-power events) total to date

by 2.8 (round up the result to the next whole number).

(2) For operators with mast, P/N 214-040-090-121, multiply the

factored flight hour total to date by 14 (round up the result to the

next whole number).

(3) Record on the component history card the accumulated RIN.

Note 2: BHTI Alert Service Bulletin (ASB) No. 214ST-94-67, dated

November 7, 1994, pertains to this subject.

(c) After complying with paragraphs (a) and (b) of this AD,

during each operation thereafter, maintain a count of the number and

type of external load lifts and the number of takeoffs performed,

and at the end of each day's operations, increase the accumulated

RIN on the component history card as follows:

(1) Increase the RIN by 2 for each takeoff.

(2) Increase the RIN by 2 for each external load lift operation;

or, increase the RIN by 4 for each external load lift operation in

which the load is picked up at a higher elevation and released at a

lower elevation, and the difference in elevation between the pickup

point and the release point is 200 feet or greater.

(d) Remove the mast, P/N 214-040-090-109 or -121, from service

on or before attaining an accumulated RIN of 140,000. The mast is no

longer retired based upon flight hours. This AD revises the

Airworthiness Limitations Section of the maintenance manual by

establishing a new retirement life for the mast of 140,000 RIN.

(e) 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, 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 3: Information concerning the existence of approved

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

obtained from the Rotorcraft Certification Office.

(f) 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.

Issued in Fort Worth, Texas, on November 5, 1996.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 96-29104 Filed 11-13-96; 8:45 am]

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