[Federal Register Volume 64, Number 234 (Tuesday, December 7, 1999)]
[Rules and Regulations]
[Pages 68277-68289]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31675]



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 Rules and Regulations
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  Federal Register / Vol. 64, No. 234 / Tuesday, December 7, 1999 / 
Rules and Regulations  

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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]
BILLING CODE 4910-13-U