Airworthiness Directives; Bell Helicopter Textron-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. 99-SW-02-AD]

Airworthiness Directives; Bell Helicopter Textron-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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to 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 that currently requires

modification and inspections of the tailboom vertical fin spar

(vertical fin spar). This action would require the same modification

and inspections plus two additional inspections, and replacement of the

vertical fin spar. This proposal is prompted by 2 accidents involving

fatigue cracks in the vertical fin spar that have occurred since the

issuance of AD 97-20-09. The actions specified by the proposed AD are

intended to prevent in-flight failure of the vertical fin spar and

subsequent loss of control of the helicopter.

DATES: Comments must be received on or before June 15, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 99-SW-02-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.

FOR FURTHER INFORMATION CONTACT: Charles Harrison, Aerospace Engineer,

FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham

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

222-5960.

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. 99-SW-02-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, (FAA), Office of the Regional Counsel, Southwest Region,

Attention: Rules Docket No. 99-SW-02-AD, 2601 Meacham Blvd., Room 663,

Fort Worth, Texas 76137.

Discussion

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 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 that result from repeated heavy lift operations

can cause fatigue cracks which will cause the vertical fin spar to

fail. After the issuance of that AD, the FAA determined that additional

model helicopters are affected by the same unsafe condition. The FAA

then issued AD 97-20-09, Amendment 39-10521, on May 4, 1998 (63 FR

26439, May 13, 1998), and added Model SW205A-1 helicopters and the Utah

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

Since the issuance of that AD, two accidents, one of which included

fatalities, have occurred. The FAA has determined that additional

inspections are needed, and replacement of the vertical fin spar, part

number (P/N) 205-030-846-all dash numbers, is required. This proposal

would require another inspection and another modification at 50 hours

TIS, and further inspections thereafter at intevals not to exceed 50

hours TIS. This proposal would also require that the vertical fin be

replaced within 12 calendar months.

Since an unsafe condition has been identified that is likely to

exist or develop on other 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 the same

type design, the proposed AD would supersede AD 97-20-09 to require

inspections, modification, and replacement of the vertical fin spar.

The FAA estimates that 75 helicopters of U.S. registry would be

affected by this proposed AD, that it would take approximately 4 work

hours to accomplish the initial inspection, 8 work hours to accomplish

the modification and the recurring inspections, and 180 hours to

replace the vertical fin spar, and that the average labor rate is $60

per work hour. Required parts would cost approximately $200 for the

modification and $15,000 for the replacement. Based on these figures,

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

to be $2,004,000 to conduct an initial inspection, modify the vertical

fin spars and conduct recurring inspections, and replace the vertical

fin spars on all helicopters in the U.S. fleet.

[[Page 18846]]

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 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-10521 (63 FR

26439, May 13, 1998), and by adding a new airworthiness directive (AD),

to read as follows:

California Department of Forestry; Firefly Aviation Helicopter

Services (Previously Erickson Air Crane Co.); Garlick Helicopters,

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

Inc.; Tamarack Helicopters (Previously Ranger Helicopter Services,

Inc.); Robinson Aircrane; Williams Helicopter Corporation

(Previously Scott Paper Co.); Smith Helicopters; Southern Helicopter

Inc.; Southwest Florida Aviation; Utah State University; Western

International Aviation, Inc.; UNC Helicopters; And U.S. Helicopter,

Inc.: Docket No. 99-SW-02-AD. Supersedes AD 97-20-09, Amendment 39-

10521, Docket No. 97-SW-35-AD.

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

H5NM), TH-lF (TCDS H12NM, and R00008AT), 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 R00008AT), UH-1H (TCDS H13WE, H3SO,

H15NM, and R00007DE), UH-lL (TCDS H5NM, H7SO, and H4NM), UH-1P (TCDS

H12NM, and R00008AT), and SW204 (TCDS H6SO), SW204HP (TCDS H6SO),

SW205 (TCDS H6SO), and SW205A-1 (TCDS H6SO) helicopters, with

tailboom vertical fin spar (vertical fin spar), part number (P/N)

205-032-899-all dash numbers, 205-030-846-all dash numbers, 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

otherwise 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 request approval for an

alternative method of compliance in accordance with paragraph (h) of

this AD. The request should include an assessment of the effect of

the modification, alteration, or repair on the unsafe condition

addressed by this AD; and, if the unsafe condition has not been

eliminated, the request should include specific proposed actions to

address it.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of the tailboom vertical fin (fin) spar and

subsequent loss of control of the helicopter, accomplish the

following:

(a) Within 8 hours time-in-service (TIS), modify the vertical

fin spar as follows:

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

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

(2) Remove the first four rivets from the fin spar located at

the bottom of the fin spar left-hand side at the tailboom and fin

spar junction, and the first four rivets aft of the junction along

the lower edge of the fin spar side-skin as shown (see Figure 2).

(3) Trim the fin spar left-hand skin using extreme care to not

damage the fin spar assembly (see Figure 3).

(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 fin spar using MS 20470AD

rivets. DO NOT install the bottom two rivets into the fin spar where

the skin was trimmed.

(6) Attach the fin spar side-skin lower edge using the rivets

specified in Figure 3.

(7) Refinish all reworked areas.

(b) After modifying the fin spar assembly, inspect the fin spar

for cracks before further flight and thereafter, at intervals not to

exceed 8 hours TIS as follows:

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

tailboom station 180 (see Figure 1).

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

cover on the fin (see Figure 1).

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

inspected with a cloth dampened with aliphatic naphtha or an

equivalent cleaning solvent.

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

bright light and an inspection mirror, inspect the 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 Figures 1 and 2).

(5) Using a bright light and a 10x or higher magnifying glass,

inspect the 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 fin spar in the same area. Special attention must be

given to the left-hand edge of the fin spar and any adjacent

surfaces between fin stations 66.31 and 71.31 (see Figure 2).

(6) If any crack is discovered on the fin spar, replace the fin

spar assembly with an airworthy fin spar assembly before further

flight.

(c) Within 50 hours TIS, and thereafter at intervals not to

exceed 50 hours TIS, inspect the fin spar assembly as follows:

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

cover on the fin spar assembly (see Figure 1). Remove the aft lower

fin fairing and fin access panels that allow access to the aft side

of the forward fin spar and the secondary spar (see Figure 1).

(2) 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, 10x or higher

magnifying glass, and a borescope as required, inspect all of the

fin ribs, fittings, skins, and secondary aft spar of the fin

assembly (see Figures 4 and 5). Pay particular attention to the

upper and lower fittings at tailboom station 227 for cracked or

corroded fittings or sheared or loose rivets.

(3) Gain access to the canted bulkhead aft of tailboom station

194.30 through the most aft lower access covers by removing the aft

access covers or position light fairings as required. Visually

inspect the canted bulkhead forward and aft sides through the lower

tailboom inspection hole and position

[[Page 18847]]

light access holes for cracks, corrosion, or loose or sheared rivets

in all skins, fittings and bulkheads using a bright light, an

inspection mirror, and a borescope as required (see Figures 4 and

5). Pay particular attention to the area in the upper forward

corners of the aft skin directly around the fin spar assembly and

the overlap area of the top skin beneath the 42 deg. gearbox for

cracks, which are only visible from the underside.

(4) Any crack found in the fin spar assembly requires

replacement with an airworthy part. Replacing the entire fin spar

configuration with an airworthy fin spar configuration that has been

demonstrated to the FAA to satisfy the structural fatigue

requirements of repeated heavy lift operations, and is approved by

the Manager, FAA, Rotorcraft Standards Staff, will constitute a

terminating action for the requirements of this AD. Any corrosion,

loose or sheared rivets, or cracked skins or ribs found within the

inspection areas must be repaired prior to further flight.

(d) Within 50 hours TIS, modify the fin spar as follows:

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

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

(2) Remove the next 10 rivets from the fin spar located at the

bottom of the fin spar left-hand side at the tailboom and fin spar

junction (see Figures 6 and 7, whichever is applicable).

Caution: Extreme care must be taken when drilling and removing

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

is not damaged.

(3) Trim the fin left-hand side skin using extreme care to not

damage the fin spar assembly to expose the spar outboard edge (See

Figure 6 or 7, whichever is applicable).

(4) Deburr the rivet holes and trimmed side skin edges. Remove

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

contaminates with a cloth that has been dampened with aliphatic

naphtha or an equivalent cleaning solvent.

(5) Fabricate cover plates in accordance with the notes and

drawings of Figure 8 or 9, whichever is applicable. Ream prepare the

holes in the fin spar and parts and install HI-LOK fasteners.

Note 2: Bell Helicopter Medium Structural Repair Manual, BHT-

MED-SRM-1, pages 3-36 through 3-38, pertains to this installation

and reaming procedure.

(6) Refinish all reworked areas, close driveshaft and replace

42 deg. gearbox cover.

(e) After modification of the fin spar assembly, before further

flight and thereafter at intervals not to exceed 100 hours TIS,

inspect the fin spar for cracks as follows:

(1) Remove the 42 deg. gearbox cover, open the driveshaft cover

on the vertical fin spar assembly, and remove the spar cover plate

and filler plate from the lower left-hand side of the fin assembly

(see Figures 1 and 8 or 9, whichever is applicable).

Caution: Extreme care must be taken when removing the cover

plate and filler from the side of the fin spar to ensure that the

spar assembly is not damaged.

(2) In a ventilated work area, clean the surface to be inspected

with a cloth dampened with aliphatic naphtha.

Caution: Do not use chemical paint strippers. Use Scotch-Brite

Grade-A VFN and methyl-ethyl ketone (MEK) or a suitable solvent to

remove the paint and primer in the inspection area.

(3) Perform a dye-penetrant inspection of the exposed area of

the fin spar (See Figures 6 and 7).

Note 3: ASTM E1416 or MIL-STD-6866, or the Bell Helicopter

Standard Practices Manual, BHT-ALL-SPM, Chapter 6.2, pertains to

this inspection.

(4) If any crack is discovered on the fin spar, replace the fin

spar assembly with an airworthy fin spar assembly before further

flight.

(5) After inspection, apply zinc chromate primer to the bare

surfaces. When dry, re-install the cover plate and the filler using

fasteners specified in Figure 8 or 9, whichever is applicable.

(6) Install the 42 deg. gearbox cover and the driveshaft cover.

(f) Within 12 calendar months, remove the fin spar, P/N 205-030-

846-all dash numbers, P/N 205-032-899-all dash numbers, or P/N 205-

032-851-all dash numbers, whichever is applicable, and replace it

with an airworthy fin spar configuration that has been demonstrated

to the FAA to satisfy the structural fatigue requirements of

repeated heavy lift operations, and is approved by the Manager, FAA,

Rotorcraft Standards Staff.

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(g) Replacing the fin spar, P/N's 205-032-899-all dash numbers,

205-030-846-all dash numbers, or 205-032-851-all dash numbers, with

an airworthy fin spar that has been demonstrated to the FAA to

satisfy the structural fatigue requirements of repeated heavy lift

operations and approved by the Manager, FAA, Rotorcraft Standards

Staff, constitutes a terminating action for the requirements of this

AD.

(h) 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, FAA, Rotorcraft Standards Staff.

Operators shall submit their requests through an FAA Principal

Maintenance Inspector, who may concur or comment and then send it to

the Manager, FAA, Rotorcraft Standards Staff.

Note 4: Information concerning the existence of approved fin

spar configurations and alternative methods of compliance with this

AD, if any, may be obtained from the Rotorcraft Standards Staff.

(i) 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 April 9, 1999.

Eric Bries,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 99-9510 Filed 4-15-99; 8:45 am]

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