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; Amendment 39-11455; AD 99-25-12]

RIN 2120-AA64

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: Final rule.

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SUMMARY: This amendment supersedes 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

amendment requires the same modification and inspections plus two

additional inspections and replacement of the vertical fin spar. This

amendment is prompted by 6 accidents, 2 of which involved fatalities,

involving fatigue cracks in the vertical fin spar that have occurred

since the issuance of AD 97-20-09. 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.

EFFECTIVE DATE: January 11, 2000.

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: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) by superseding AD 97-20-09,

Amendment 39-10521 (63 FR 26439, May 13, 1998), Docket No. 97-SW-35-AD,

which is 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, SW205, and SW205A-1

helicopters, was published in the Federal Register on April 16, 1999

(64 FR 18845). That action proposed to require the same modification

and inspections of the vertical fin spar as required by AD 97-20-09

plus additional inspections and replacement of the vertical fin spar,

part number (P/N) 205-030-846-all dash numbers.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter states that the AD should be made applicable only to

operators that are using the affected helicopters in logging

operations. The commenter feels that the accidents that have occurred

were due to the aircraft being involved in logging operations and

states that the two accidents referred to in AD 97-20-09 were caused by

operators not performing AD 97-20-09. The commenter also states that

the AD is unnecessary and cost prohibitive to those operators who do

not perform logging operations. The FAA does not concur; cracks have

been found in the vertical fin spar on aircraft that have had no

operational time performing heavy lift operations. The FAA believes

that this service difficulty stems from the repeated demand for high

power from the helicopter regardless of the type of operation.

Another commenter states that (1) vertical fin failures are due to

a combination of improper operation of the aircraft and/or helicopter

inspection procedures and (2) the FAA's economic analysis estimate is

25 to 40% too low. The FAA partially concurs. As stated previously,

cracks in the vertical fin are not necessarily directly related to

heavy lift operation but to repeated demand for high-power. The

commenter acknowledges that its cost estimate is based on modifications

performed on other aircraft; those modifications were more substantial

than the modifications proposed by the NPRM. The FAA is aware that

currently there is only one spar approved for specific type

certificated restricted category helicopters that meets the repeated

high torque event substantiation requirements of this AD; the cost for

that spar was used in the economic analysis. There are other persons

who have applied for and are working on certification of other spars.

Therefore the FAA agrees that the cost of those spars may be higher

than the cost of the spars used in its economic analysis. However,

there remains no better information upon which the FAA can rely.

Additionally, the commenter offered suggestions for an alternate method

of compliance (AMOC) to the actions specified in the NPRM. The

suggestions included: (1) Allowing the installation of supplemental

type certificate (STC) SR00267SE with 212-030-447-101 or -117 spar; (2)

assigning a life limit to all vertical fin spars for Bell-manufactured

medium helicopters and require the installation of an exceedance-

monitoring device with an uninterrupted data history. The first

suggestion from the commenter cannot be adopted at this time because

the fatigue substantiation for the cited STC did not include the

effects of repeated high torque events during certification. However,

if this is accomplished, the FAA will consider this option. The second

suggestion cannot be adopted for various reasons. The first is that the

type certificate holders of approved fin spars have chosen not to

impose life limits on their installations and, rather than imposing

life limits, the FAA feels that the current installation of ``laminated

fin spars'' should be removed from service due to the nature of the

failure mode of this part and the current safety problems that are

being experienced with this particular design. Also, the FAA knows of

no certified monitoring systems being installed on restricted category

aircraft that may be used for maintenance credits.

An additional commenter states that the use of the words ``repeated

heavy lift operations'' attempts to place the blame for those spar

failures on the logging industry. The commenter states that the

[[Page 68278]]

cause of the fin spar failures was the repeated application of engine

torque and the tail rotor reaction thereof, not what was in the

helicopter or hanging from the external hook. The commenter states that

it is improper to infer logging by using the term ``heavy lift

operation;'' it should use the term ``high torque events.'' The FAA

concurs and has changed the wording in this AD to ``repeated high

torque events.''

Another commenter states that Note 1 of the NPRM could be

interpreted to impose undue/unnecessary burden on operators who have

incorporated a modified commercial vertical fin assembly. The commenter

further states that the proposed AD should not apply to his particular

vertical fin assembly, which has been issued an STC. The FAA does not

concur; the particular STC has not been substantiated or shown to meet

the requirements of ``repeated high torque events.''

The same commenter states that the requirement to meet repetitive

heavy lift structural limitations has been imposed on specific flight

profiles and it imposes undue burden on heavy lift operators who have

already spent money installing an STC which includes a spar

configuration that has not been shown to meet the proposed fatigue

requirements. The FAA does not concur that fatigue substantiation to

correct an unsafe condition is imposing an undue burden on a particular

set of operators. The NPRM for this AD was followed by other AD's that

were applicable to the commercial equivalent model helicopters. In

fact, any applicant for an AMOC, STC, type certificate, or other type

of approval will be required to meet the same repeated high torque

events requirements.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule as proposed except that the

term ``repeated heavy lift'' will be replaced by ``repeated high torque

events.'' Also, two other nonsubstantive changes have been made to

paragraph (h) and Note 4 of the AD. In paragraph (h), the NPRM

incorrectly states that alternative methods of compliance (AMOC) or

adjustments of the compliance time may be approved by the ``Manager,

Rotorcraft Standards Staff, Rotorcraft Directorate.'' This is incorrect

and has been changed to state that the Manager, Regulations Group,

Rotorcraft Directorate, is responsible for approving any AMOC or

adjustment of the compliance time. Note 4 of the NPRM states that

information concerning the existence of approved AMOC may be obtained

from the ``Rotorcraft Standards Staff;'' this is also incorrect and has

been changed to state that information may be obtained from the

``Regulations Group.'' The FAA has determined that these changes will

neither increase the economic burden on any operator nor increase the

scope of the AD.

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

affected by this AD, that it will take approximately 4 work hours to

accomplish the initial inspection, 8 work hours to accomplish the

initial and recurring inspections, 180 work hours to replace the

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

hour. Required parts will cost approximately $200 for the modification

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

impact of the 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.

The regulations adopted herein will not have a substantial direct

effect 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, it

is determined that this final rule does not have federalism

implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the FAA, Office of the Regional Counsel,

Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas

76137.

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 removing Amendment 39-10521 (63 FR

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

Amendment 39-11455, to read as follows:

AD 99-25-12 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.: Amendment 39-11455. 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:

[[Page 68279]]

(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 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 high-torque events 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 high torque events, 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 high torque

events 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, Regulations Group, 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, Regulations Group.

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 Regulations Group.

(i) 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.

(j) This amendment becomes effective on January 11, 2000.

Issued in Fort Worth, Texas, on November 30, 1999.

Mark R. Schilling,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 99-31675 Filed 12-6-99; 8:45 am]

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