Airworthiness Directives; Bell Helicopter Textron (Bell) Model 204B, 205A, and 205A-1 Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-32-AD; Amendment 39-10520; AD 97-18-11]

RIN 2120-AA64

Airworthiness Directives; Bell Helicopter Textron (Bell) Model

204B, 205A, and 205A-1 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment

adopting Airworthiness Directive (AD) 97-18-11, issued on August 29,

1997, which was sent previously to all known U.S. owners and operators

of Bell Model 204B, 205A, and 205A-1 helicopters by individual letters.

This AD requires modification and inspections of the vertical fin spar.

If any crack is discovered, replacement of the vertical fin spar with

an airworthy vertical fin spar is required before further flight. This

amendment is prompted by several failures of the vertical fin spar,

including those with steel doublers, caused by fatigue cracks that

result from a large number of high-power events. The actions specified

by this AD are intended to prevent in-flight failure of the vertical

fin spar and subsequent loss of control of the helicopter.

DATES: Effective May 28, 1998, to all persons except those persons to

whom it was made immediately effective by priority letter AD 97-18-11,

issued on August 29, 1997, which contained the requirements of this

amendment.

Comments for inclusion in the Rules Docket must be received on or

before July 13, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Office of the Regional Counsel, Southwest Region,

Attention: Rules Docket No. 97-SW-32-AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Charles Harrison, Aerospace

Engineer, FAA, Rotorcraft Directorate, Rotorcraft Certification Office,

2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5447,

fax (817) 222-5783.

SUPPLEMENTARY INFORMATION: On August 29, 1997, the FAA issued priority

letter AD 97-18-11, applicable to Bell Model 204B, 205A, and 205A-1

helicopters, which requires modification and inspections of the

vertical fin spar. If any crack is discovered, replacement of the

vertical fin spar with an airworthy vertical fin spar is required

before further flight. Priority letter AD 97-18-11 superseded priority

letter AD 97-18-01, issued on August 19, 1997. AD 97-18-01 contained

the same basic requirements as is contained in AD 97-18-11. However, AD

97-18-11 was needed to clarify the method of compliance for the Model

204B helicopters, and to correct an error in a vertical fin spar part

number (P/N). AD 97-18-01 incorrectly stated the P/N as P/N 205-030-851

instead of P/N 205-032-851. This AD is prompted by an accident

involving the in-flight failure of the vertical fin spar on a Model

205A-1 helicopter. Two other accidents on restricted category (military

surplus) aircraft of similar type design have occurred. One of the

accidents resulted in a fatality. In 1971, the FAA issued AD 71-21-02,

which addressed this problem by requiring the addition of a steel

doubler to the inside edge of the vertical fin spar. There have been

several additional failures since that AD was issued. A large number of

high-power events can cause fatigue cracks which will cause the

vertical fin spar to fail. This condition, if not corrected, could

result in in-flight failure of the vertical fin spar and subsequent

loss of control of the helicopter.

Since the unsafe condition described is likely to exist or develop

on other Bell

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Model 204B, 205A, and 205A-1 helicopters of the same type design, the

FAA issued priority letter AD 97-18-11 to prevent in-flight failure of

the vertical fin spar and subsequent loss of control of the helicopter.

The AD requires, within 8 hours time-in-service (TIS) after the

effective date of this AD, modification and inspection of the vertical

fin spar. Then, at intervals not to exceed 8 hours TIS, further

inspections of the vertical fin spar for cracks are required. If any

crack is discovered, replacement of the vertical fin spar with an

airworthy vertical fin spar is required before further flight.

Since it was found that immediate corrective action was required,

notice and opportunity for prior public comment thereon were

impracticable and contrary to the public interest, and good cause

existed to make the AD effective immediately by individual letters

issued on August 29, 1997 to all known U.S. owners and operators of

Bell Model 204B, 205A, and 205A-1 helicopters. These conditions still

exist, and the AD is hereby published in the Federal Register as an

amendment to section 39.13 of the Federal Aviation Regulations (14 CFR

39.13) to make it effective to all persons.

The FAA estimates that 265 helicopters will be affected by this

proposed AD, that it will take approximately 203 work hours to

accomplish the modification, inspection, and spar replacement, and that

the average labor rate is $60 per work hour. Based on these figures,

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

$3,227,700.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 97-SW-32-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and that it is not a ``significant regulatory

action'' under Executive Order 12866. It has been determined further

that this action involves an emergency regulation under DOT Regulatory

Policies and Procedures (44 FR 11034, February 26, 1979). If it is

determined that this emergency regulation otherwise would be

significant under DOT Regulatory Policies and Procedures, a final

regulatory evaluation will be prepared and placed in the Rules Docket.

A copy of it, if filed, 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. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

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

(AD) to read as follows:

AD 97-18-11 Bell Helicopter Textron: Amendment 39-10520. Docket

No. 97-SW-32-AD.

Applicability: Model 204B, 205A, and 205A-1 helicopters, with

tailboom vertical fin spar, part number (P/N) 205-032-899, 205-030-

846, or 205-032-851, all dash numbers, 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 (c) 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 in-flight failure of the tailboom vertical

fin spar (vertical fin spar) and subsequent loss of control of the

helicopter, accomplish the following:

(a) For Model 204B helicopters, within 8 hours time-in-service

(TIS) after the effective date of this AD, modify the vertical fin

spar as follows:

(1) Remove the 42 deg. gearbox cover and open the drive shaft

cover on the vertical fin spar assembly (see Figure 1).

(i) Remove the first four rivets from the vertical fin spar

located at the bottom of the vertical fin spar left-hand side at the

tailboom and vertical fin spar junction, and the first four rivets

aft of the junction along the lower edge of the vertical fin spar

skin (skin) as shown (see Figure 2). CAUTION: Extreme care must be

taken when drilling and removing rivets from the side of vertical

fin spar to ensure the vertical fin spar assembly is not damaged.

(ii) Trim the vertical fin spar left-hand skin using extreme

care to not damage the vertical fin spar assembly (see Figure 3).

(iii) Deburr the rivet holes and trimmed skin edges. Remove all

debris. In a ventilated work area, remove any surface contaminants

with a cloth that has been dampened with aliphatic naphtha or an

equivalent cleaning solvent.

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(iv) Reattach the skin to the vertical fin spar using MS 20470AD

rivets. DO NOT install the bottom two rivets into the vertical fin

spar where the skin was trimmed.

(v) Reinstall the vertical fin spar skin lower edge rivets using

M 7885/6-5 rivets (see Figure 6).

(vi) Refinish all reworked areas.

(vii) After modifying the vertical fin spar, immediately inspect

the vertical fin spar in accordance with paragraphs (a)(2)(iii) and

(a)(2)(iv) of this AD.

(2) After the initial modification and inspection of the

vertical fin spar have been accomplished in accordance with

paragraph (a)(1) of this AD, thereafter, at intervals not to exceed

8 hours TIS, inspect the vertical fin spar in accordance with

paragraphs (a)(2)(iii) and (a)(2)(iv) of this AD for cracks as

follows:

(i) Remove the lower aft tailboom inspection door, located at

tailboom station 180 (see Figure 4).

(ii) Remove the 42 deg. gearbox cover and open the drive shaft

cover on the vertical fin (see Figure 1).

(iii) Through the lower aft tailboom inspection door, using a

bright light and an inspection mirror, inspect the vertical fin spar

assembly adjacent to the tailboom top skin on the forward side,

paying special attention to the left-hand edge and the adjacent

surfaces (see Figure 5).

(iv) In a ventilated work area, clean all surfaces to be

inspected with a cloth dampened with aliphatic naphtha or an

equivalent cleaning solvent. Using a bright light and a 10x

magnifying glass, inspect the vertical fin spar assembly adjacent to

the tailboom top-skin on the in-board and out-board sides, the

vertical edge, and the two open rivet holes. Using a bright light

and a mirror, inspect the aft side of the vertical fin spar in the

same area. Special attention must be given to the left-hand edge of

the vertical fin spar and any adjacent surfaces between fin stations

66.31 and 71.31 (see Figure 5).

(3) If any crack is discovered on the vertical fin spar as a

result of the inspection specified in paragraphs (a)(2)(iii) or

(a)(2)(iv) of this AD, replace the vertical fin spar assembly with

an airworthy vertical fin spar assembly before further flight.

(b) For Model 205A and 205A-1 helicopters, within 8 hours TIS

after the effective date of this AD, modify the vertical fin spar as

follows:

(1) Remove the 42 deg. gearbox cover and open the drive shaft

cover on the vertical fin spar assembly (see Figure 1).

(i) Remove the clip, P/N 212-030-099-091, and the radius block,

P/N 212-030-099-095, (see Figures 5 and 6).

(ii) Remove the first four rivets from the vertical fin spar,

located at the bottom of the vertical fin spar left-hand side at the

tailboom and vertical fin spar junction as shown (see Figure 5).

CAUTION: Extreme care must be taken when drilling and removing

rivets from the side of vertical fin spar to ensure the vertical fin

spar assembly is not damaged.

(iii) Trim the vertical fin left-hand side skin and retainer, P/

N 205-032-851-045, using extreme care to not damage the vertical fin

spar assembly (see Figure 7).

(iv) Deburr the rivet holes and trimmed retainer and skin edges.

Remove all debris. In a ventilated work area, remove any surface

contaminants with a cloth that has been dampened with aliphatic

naphtha or an equivalent cleaning solvent.

(v) Reattach the skin and retainer to the vertical fin spar

using MS 20470AD rivets. DO NOT install the bottom two rivets into

the vertical fin spar where the skin and retainer were trimmed.

(vi) Reinstall the clip and radius block with M 7885/6-5 rivets

(see Figure 5).

(vii) Refinish all reworked areas.

(viii) After modifying the vertical fin spar, immediately

inspect the vertical fin spar in accordance with paragraphs

(b)(2)(iii) and (b)(2)(iv) of this AD.

(2) After the initial modification and inspection of the

vertical fin spar have been accomplished in accordance with

paragraph (b)(1) of this AD, thereafter, at intervals not to exceed

8 hours TIS, inspect the vertical fin spar in accordance with

paragraphs (b)(2)(iii) and (b)(2)(iv) of this AD for cracks as

follows:

(i) Remove the lower aft tailboom inspection door, located at

tailboom station 180 (see Figure 4).

(ii) Remove the 42 deg. gearbox cover and open the drive shaft

cover on the vertical fin spar (see Figure 1).

(iii) Through the lower aft tailboom inspection door, using a

bright light and an inspection mirror, inspect the vertical fin spar

assembly adjacent to the tailboom top skin on the forward side,

paying special attention to the left-hand edge and the adjacent

surfaces (see Figure 5).

(iv) In a ventilated work area, clean all surfaces to be

inspected with a cloth dampened with aliphatic naphtha or an

equivalent cleaning solvent. Using a bright light and a 10x

magnifying glass, inspect the vertical fin spar assembly adjacent to

the tailboom top-skin on the in-board and out-board sides, the

vertical edge and the two open rivet holes. Using a bright light and

a mirror, inspect the aft side of the vertical fin spar in the same

area. Special attention must be given to the left-hand edge of the

vertical fin spar and any adjacent surfaces between fin stations

66.31 and 71.31 (see Figure 5).

(3) If any crack is discovered on the vertical fin spar as a

result of the inspection specified in paragraphs (b)(2)(iii) or

(b)(2)(iv) of this AD, replace the vertical fin spar assembly with

an airworthy vertical fin spar assembly before further flight.

(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, Rotorcraft Certification Office,

FAA. 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.

(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 helicopter to a location where the

requirements of this AD can be accomplished.

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(e) This amendment becomes effective on May 28, 1998, to all

persons except those persons to whom it was made immediately effective

by Priority Letter AD 97-18-11, issued August 29, 1997, which contained

the requirements of this amendment.

Issued in Fort Worth, Texas, on May 4, 1998.

Eric Bries.

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 98-12508 Filed 5-12-98; 8:45 am]

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