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

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-SW-26-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 adoption of a new airworthiness

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

(BHTI) Model 214ST helicopters with certain tailboom assemblies and a

certain emergency float kit installed. This proposal would require

initial and repetitive inspections of the tailboom for cracks until

modifications of the tailboom are accomplished. This proposal is

prompted by several reports of cracks in the lower aft skin of the

tailboom assembly. The actions specified by the proposed AD are

intended to prevent cracks in the tailboom assembly, which could result

in structural failure of the tailboom and subsequent loss of control of

the helicopter.

DATES: Comments must be received by January 2, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Rules Docket No. 95-SW-26-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., Attention: Customer

Support, P.O. Box 482, Fort Worth, Texas 76101. This information may be

examined at the FAA, Office of the Assistant Chief Counsel, 2601

Meacham Blvd., Room 663, Fort Worth, Texas.

FOR FURTHER INFORMATION CONTACT: Mr. Tom Henry, Aerospace Engineer,

FAA, Rotorcraft Directorate, Rotorcraft Certification Office, 2601

Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5158, 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. 95-SW-26-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. 95-SW-26-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas

76137.

Discussion

This document proposes to adopt a new AD that is applicable to BHTI

Model 214ST helicopters, serial number (S/N) 28101 through 28132, with

a tailboom assembly, part number (P/N) 214-031-003-111 or 214-031-003-

277, and with an emergency float kit, P/N 214-706-120, installed. There

have been reports of cracks found in five Model 214ST helicopter

tailbooms with the emergency float kit installed. The cracks were found

in the lower aft skin between boom stations 243.76 and 284.38. This

condition, if not corrected, could result in structural failure of the

tailboom and subsequent loss of control of the aircraft.

The FAA has reviewed Bell Helicopter Textron, Inc. Alert Service

Bulletin 214ST-95-72 (ASB), dated July 24, 1995, which describes

procedures for a visual inspection of the affected tailboom area of

Model 214ST helicopters with emergency float kits installed. The ASB

also describes a modification to the helicopters that adds internal

stiffeners and doublers to the tailboom, and replaces the existing

access door frame, P/N 214-030-325, with a redesigned frame of

increased thickness.

Since an unsafe condition has been identified that is likely to

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

same type design, the proposed AD would require, for Model 214ST

helicopters, S/N 28101 through 28132, with a tailboom assembly, P/N

214-031-003-111 or 214-031-003-277, and with an emergency float kit, P/

N 214-706-120, installed, inspections of the tailboom assembly for

cracks within 250 hours time-in-service (TIS) or at the next 180-day

float inspection, and thereafter, at each 180-day float inspection

until certain modifications of the tailboom are accomplished. The

modifications, which are to be accomplished if any crack is found in

the tailboom or on or before accumulating an additional 500 hours TIS

after the effective date of this AD, whichever occurs first, include

installing stiffeners and doublers in the tailboom, and replacing the

access door frame with a thicker access door frame. The actions would

be required to be accomplished in accordance with the procedures

contained in BHTI Alert Service Bulletin (ASB) 214ST-95-72, dated July

24, 1995.

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

affected by this proposed AD, that it would take approximately 20 work

[[Page 55496]]

hours per helicopter to accomplish the modifications, approximately 3

work hours per helicopter to accomplish the 250 hours TIS inspection,

and that the average labor rate is $60 per work hour. Required parts

would cost approximately $1,100 per helicopter. Based on these figures,

the total cost impact of the proposed AD on U.S. operators is estimated

to be $14,880.

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 USC 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive

to read as follows:

Bell Helicopter Textron, Inc. (BHTI): Docket No. 95-SW-26-AD.

Applicability: Model 214ST helicopters, serial number (S/N)

28101 through 28132, with a tailboom assembly, part number (P/N)

214-031-003-111 or 214-031-003-277 and with an emergency float kit,

P/N 214-706-120, 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 (d) 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 as indicated, unless accomplished

previously.

To prevent cracks in the tailboom assembly, structural failure

of the tailboom and subsequent loss of control of the helicopter,

accomplish the following:

(a) Within the next 250 hours time-in-service (TIS) or at the

next 180-day float inspection, whichever occurs first, and

thereafter at intervals not to exceed each 180-day float inspection,

visually inspect the tailboom assembly for cracks in accordance with

the maintenance procedures contained in Part 1 of the Accomplishment

Instructions of BHTI Alert Service Bulletin 214ST-95-72, dated July

24, 1995.

(b) Upon discovery of a crack or on or before accumulating an

additional 500 hours TIS after the effective date of this AD,

whichever occurs first, modify the tailboom assembly in accordance

with Part 2 of the Accomplishment Instructions of BHTI Alert Service

Bulletin No. 214ST-95-72, dated July 24, 1995.

(c) Modification of the tailboom assembly in accordance with

paragraph (b) constitutes terminating action for the 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 when approved by the Manager, Rotorcraft Certification Office.

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 2: Information concerning the existence of approved

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

obtained from the Rotorcraft Certification Office.

(e) 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 October 23, 1995.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 95-27000 Filed 10-31-95; 8:45 am]

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