Airworthiness Directives; Bell Helicopter Textron (Bell)- manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH- 1H, UH-1L, and UH-1P Helicopters; and Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1 Helicopters

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-35-AD; Amendment 39-10521; AD 97-20-09]

RIN 2120-AA64

Airworthiness Directives; Bell Helicopter Textron (Bell)-

manufactured Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-

1H, UH-1L, and UH-1P Helicopters; and Southwest Florida Aviation SW204,

SW204HP, SW205, and SW205A-1 Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment supersedes an existing priority letter

airworthiness directive (AD), applicable to Bell-manufactured Model HH-

1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P

helicopters; and Southwest Florida Aviation SW204, SW204HP, and SW205

helicopters, that currently requires modification and inspections of

the vertical fin spar. This amendment requires the same modification

and inspections required by the existing priority letter AD, but adds

the Southwest Florida Aviation Model SW205A-1 and Utah State University

UH-1H helicopters to the applicability of this AD. This amendment is

prompted by accidents involving in-flight failure of the tailboom

vertical fin spar. 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.

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-35-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) 222-5960.

[[Page 26440]]

SUPPLEMENTARY INFORMATION: On September 17, 1997, the FAA issued

priority letter AD 97-20-09, applicable to Bell-manufactured Model HH-

1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P

helicopters; and Southwest Florida Aviation SW204, SW204HP and SW205

helicopters, which requires modification and inspections of the

vertical fin spar. That priority letter AD was prompted by two

accidents involving in-flight failures of the tailboom vertical fin

spars (vertical fin spars) on Model TH-lL and UH-1B helicopters. One

other accident occurred on a Model 205A-1 helicopter which is of

similar type design. One of the accidents resulted in a fatality. As a

result of those accident investigations, the FAA determined that 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 issuance of that priority letter AD, the FAA has

determined that additional helicopter models are affected by the same

unsafe condition.

Since an unsafe condition has been identified that is likely to

exist or develop on other Bell-manufactured Model HH-1K, TH-1F, TH-1L,

UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters; and

Southwest Florida Aviation SW204, SW204HP, SW205, and SW205A-1

helicopters of a similar type design, this AD supersedes priority

letter AD 97-20-09 to add the Model SW205A-1 helicopters and the Utah

State University UH-1H helicopters to the applicability of this AD. The

short compliance time involved is required because the previously

described critical unsafe condition can adversely affect the structural

integrity of the helicopter. Therefore the inspections and modification

are required within 8 hours time-in-service and this AD must be issued

immediately.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

The FAA estimates that 68 helicopters of U.S. registry would be

affected by this proposed AD, that it would take approximately 2.5 work

hours per helicopter for the initial modification and inspection, 200

work hours to replace the vertical fin spar, and that the average labor

rate is $60 per work hour. Required parts would cost approximately

$8,000 per helicopter to replace the vertical fin spar. Based on these

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

estimated to be $1,370,200 to modify the vertical fin, conduct an

initial inspection, and replace the vertical fin spars on all

helicopters in the U.S. fleet.

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-35-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,

[[Page 26441]]

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), Amendment 39-10521, to read as follows:

AD 97-20-09 California Department of Forestry; Firefly Aviation

Helicopter Services (Previously Erickson Air Crane Co.); Garlick

Helicopters, Inc.; Hawkins and Powers Aviation, Inc.; International

Helicopters, Inc.; Ranger Helicopter Services; Robinson Aircrane;

Scott Paper Co.; Smith Helicopters; Southern Helicopter; Southwest

Florida Aviation; Utah State University; Western International

Aviation, Inc.; UNC Helicopters; and U.S. Helicopter, Inc.:

Amendment 39-10521. Docket No. 97-SW-35-AD. Supersedes priority

letter AD 97-20-09.

Applicability: Model HH-1K (Type Certificate Data Sheet (TCDS)

H5NM), TH-lF (TCDS H12NM, and R0008AT), TH-1L (TCDS H5NM, H7SO, and

H4NM), UH-1A (TCDS H3SO), UH-1B (TCDS H1RM, H3NM, H13WE, H3SO, H5SO,

and R00012AT), UH-1E (TCDS H5NM, H7SO, H8NM, and H4NM), UH-1F (TCDS

H2NM, H7NE, H11SW, H12NM, and R0008AT), UH-1H (TCDS H13WE, H3SO, and

H15NM), UH-lL (TCDS H5NM, H7SO, and H4NM), UH-1P (TCDS H12NM, and

R0008AT), and SW204 (TCDS H6SO), SW204HP (TCDS H6SO), SW205 (TCDS

H6SO), and SW205A-1 (TCDS H6SO) 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 (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 in-flight failure of the tailboom vertical fin spar

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

helicopter, accomplish the following:

(a) 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).

[[Page 26442]]

[GRAPHIC] [TIFF OMITTED] TR13MY98.026

(2) 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

side-skin as shown (see Figure 2).

Caution: Extreme care must be taken when drilling and removing

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

fin spar assembly is not damaged.

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[[Page 26443]]

[GRAPHIC] [TIFF OMITTED] TR13MY98.027

(3) Trim the vertical fin spar left-hand skin using extreme care to

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

[[Page 26444]]

[GRAPHIC] [TIFF OMITTED] TR13MY98.028

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[[Page 26445]]

(4) 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.

(5) Reattach the side-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.

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

M 7885/6-5 rivets (see Figure 2).

(7) Refinish all reworked areas.

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

the vertical fin spar in accordance with paragraphs (b)(3) and

(b)(4) of this AD.

(b) After the initial modification and inspection of the

vertical fin spar have been accomplished in accordance with

paragraph (a) of this AD, thereafter, at intervals not to exceed 8

hours TIS, inspect the vertical fin spar for cracks as follows:

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

tailboom station 180 (see Figure 4).

[GRAPHIC] [TIFF OMITTED] TR13MY98.029

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

cover on the vertical fin (see Figure 1).

(3) 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 2).

(4) 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 2).

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

result of the inspection specified in paragraphs (b)(3) or (b)(4) of

this AD, replace the vertical fin spar assembly with an airworthy

vertical fin spar assembly before further flight.

(d) 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.

(e) 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.

(f) This amendment becomes effective on May 28, 1998.

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

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 98-12509 Filed 5-12-98; 8:45 am]

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