[Federal Register Volume 64, Number 62 (Thursday, April 1, 1999)]
[Rules and Regulations]
[Pages 15661-15669]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-7778]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-SW-31-AD; Amendment 39-11101; AD 99-07-15]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Bell Helicopter Textron, Inc. (BHTI)-manufactured 
Model HH-1K, SW204, SW204HP, SW205, SW205A-1, TH-1F, TH-1L, UH-1A, UH-
1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P helicopters. This action 
requires inspecting the tail rotor yoke (yoke) assembly historical 
records to determine if the affected yoke assembly has been involved in 
any incidents that may have induced a bending load. It further requires 
replacement of the yoke assembly with a yoke assembly that has been x-
ray diffraction inspected or has zero hours time-in-service (TIS); 
installing and inspecting an airworthy flapping stop or trunnion 
assembly to detect excessive bending loads; and revising the applicable 
Rotorcraft Flight Manual. This amendment is prompted by in-flight 
failures of yokes installed on civilian and military helicopters of 
similar type design, including three reported accidents. The actions 
specified in this AD are intended to detect static or dynamic overload 
on the yoke due to external bending forces, which could result in 
failure of the yoke, loss of the tail rotor, and subsequent loss of 
control of the helicopter.

DATES: Effective May 3, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before June 1, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 98-SW-31-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Charles Harrison, Aerospace Engineer, 
FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham 
Blvd., Fort Worth, Texas 76137, telephone (817) 222-5128, fax (817) 
222-5961.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to BHTI-manufactured Model HH-1K, SW204, SW204HP, SW205, 
SW205A-1, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and 
UH-1P helicopters. This action requires, before further flight, 
inspecting the yoke assembly historical records to determine if it has 
been involved in any incidents that may have induced a bending load in 
the yoke, and if so, immediately replacing the yoke assembly with a 
yoke assembly that has been x-ray diffraction inspected or has zero 
hours TIS as well as replacing the flapping stop or trunnion assembly. 
It further requires, within the next 180 calendar days, for yokes other 
than those that are required to be replaced before further flight, 
removing and replacing the yoke assembly with an airworthy assembly. 
This AD also requires inspection of the replaced trunnion assembly or 
flapping stop at intervals not to exceed 25 hours time-in-service 
(TIS), or before further flight, after any incident involving a hard 
landing, or any other incident involving excessive tail rotor flapping 
loads. Examples of bending loads include high wind gusts (such as those 
from prop blast), improper ground handling (in which the tail rotor 
blade has been used as a hand hold), improper feathering bearing 
removal (in which the yoke is not properly supported when pressing out 
bearings), or a static ground strike of some type (such as being struck 
by a vehicle). This amendment is prompted by reports of in-flight 
failures of yokes installed on civilian and military helicopters of 
similar type design, including 3 reported accidents. The actions 
specified in this AD are intended to detect static or dynamic overload 
on the yoke due to external bending forces, which could result in 
failure of the yoke, loss of the tail rotor, and subsequent loss of 
control of the helicopter.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other BHTI Model HH-1K, SW204, SW204HP, SW205, 
SW205A-1, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and 
UH-1P helicopters of the same type design, this AD is being issued to 
detect static or dynamic overload on the yoke due to excessive bending 
forces, which could result in failure of the yoke, loss of the tail 
rotor, and subsequent loss of control of the helicopter. The short 
compliance time involved is required because the previously described 
critical unsafe condition can adversely affect the controllability and 
structural integrity of the helicopter tail rotor. Therefore, the 
actions contained in the AD are required prior to further flight, 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.

Cost Impact

    The FAA estimates that 75 helicopters will be affected by this AD, 
that it will take approximately 9 work hours to accomplish the 
inspections and installations, and that the average labor rate is $60 
per work hour. Required parts will cost approximately $6,637 per yoke, 
and $936 per flapping stop or $1,028 per trunnion. Based on these 
figures, the total cost impact of the AD on U.S. operators is estimated 
to be $608,475 to replace the yoke and flapping stop in the entire 
fleet, or $615,375 to replace the yoke and trunnion in the entire 
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

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    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. 98-SW-31-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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 
to read as follows:

AD. 99-07-15  California Department of Forestry; Firefly Aviation 
Helicopter Services (Previously Erickson Air-Crane); Garlick 
Helicopters; Hawkins & Powers Aviation, Inc.; International 
Helicopters, Inc.; Ranger Helicopter Services; Robinson Aircrane, 
Inc.; Scott Paper Co. (Formerly Off Shore); Smith Helicopters; 
Southern Helicopter, Inc.; Southwest Florida Aviation; Utah State 
University; UNC Helicopter Inc. (Formerly Williams Helicopter); US 
Helicopter, Inc.; and Western International Aviation Inc.: Amendment 
39-11101. Docket No. 98-SW-31-AD. q

    Applicability: Model HH-1K (Type Certificate Data Sheet (TCDS) 
H5NM), TH-1F (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-1L (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 tail rotor yoke, 
part number (P/N) 212-011-702-all dash numbers, P/N 212-010-704-all 
dash numbers, or P/N 212-010-744-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 (g) 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 detect static or dynamic overload on the tail rotor yoke 
(yoke) due to external bending forces, which could result in failure 
of the yoke, loss of the tail rotor, and subsequent loss of control 
of the helicopter, accomplish the following:
    (a) Before further flight, review all historical records of the 
helicopter and the identified yoke assembly for any static or 
dynamic incident history that could have imposed an excessive 
bending load on the yoke. If such a history exists, before further 
flight, replace the yoke assembly with a yoke assembly specified in 
paragraph (c) and install the flapping stop or trunnion assembly as 
specified in paragraph (d).

    Note 2: Examples of excessive bending loads include exposure to 
high wind gusts (such as those from rotor wash or prop blast), 
improper ground handling (in which the tail rotor blade has been 
used as a hand hold), improper feathering bearing removal (in which 
the yoke is not properly supported when pressing out bearings), or 
an incident in which a damaged tail rotor blade was replaced due to 
a static ground blade strike.

    (b) Identify the trunnion assembly or flapping stop that is 
installed on the aircraft tail rotor assembly to determine if it is 
a flapping stop or trunnion and, if it is a flapping stop, to 
determine if the correct flapping stop is installed (see Figures 1 
and 2).

    Note 3: Helicopters with yoke assemblies, P/N 212-010-704-all 
dash numbers or P/N 212-010-744-all dash numbers, have trunnion 
assemblies installed that look similar. Trunnion assemblies, P/N 
205-012-716-001 and P/N 212-010-703-001, are manufactured from 
machined material and do not have the proper characteristics to act 
as a yield indicators for the yoke assembly. When installed, these 
trunnion assemblies may be identified by the presence of a flanged 
bushing (split lines) at each bolt hole, readily visible externally 
when viewed inboard of the trunnion halves adjacent to each bearing. 
The trunnion assembly, P/N 212-010-738-001, is manufactured from a 
casting and does not incorporate bushings at the bolt locations. No 
bushing will be visible when viewing the assembled trunnion. 
Helicopters with yoke assemblies, P/N 212-011-702-all dash numbers, 
are assembled with a flapping stop configuration. The original 
flapping stop, P/N 212-011-713-001 has been redesigned. The 
redesigned flapping stop, P/N 212-011-713-103, will act as a yield 
indicator to provide visual verification of a yoke assembly that has 
been subjected to excessive out-of-plane bending loads (see Figure 
5).

    (c) Within the next 180 calendar days (for yokes not replaced 
immediately in accordance with paragraph (a) of this AD), remove the 
yoke assembly and replace it with an airworthy yoke assembly having 
zero hours time-in-service (TIS), or with an airworthy yoke assembly 
(regardless of TIS) that has passed an X-ray diffraction inspection 
in accordance with Part II of Bell Helicopter Textron, Inc. Alert 
Service Bulletin 212-96-100, Revision A, dated May 18, 1998.
    (d) When the yoke assembly is replaced, for helicopters with a 
yoke assembly, P/N 212-011-702-all dash numbers, install an 
airworthy tail rotor flapping stop, P/N 212-011-713-103, and for 
helicopters with yoke assemblies, P/N 212-010-704-all dash numbers 
or P/N 212-010-744-all dash numbers, install an airworthy trunnion 
assembly, P/N 212-010-738-001. If any incident as described in 
paragraph (a) of this AD occurs after the effective date of this AD 
and prior to compliance with paragraph (c), then compliance with 
paragraphs (c) and (d) is required before further flight.

    Note 4: Yoke assemblies that have passed an x-ray diffraction 
inspection at BHTI will have the letters ``FM'' vibro-etched on them 
following the serial number.

    (e) After accomplishing the requirements of paragraphs (c) and 
(d) of this AD, thereafter,

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at intervals not to exceed 25 hours TIS, or before further flight 
after any incident as described in paragraph (a) of this AD, inspect 
the trunnion assembly or flapping stop as follows:
    (1) Gain access to the tail rotor assembly to allow close 
viewing of the inboard section of the trunnion assembly or flapping 
stop, whichever is installed. Perform a visual inspection of the 
inboard section of the trunnion assembly (see Figure 3) or the 
flapping stop (see Figure 4) for deformation. Inspect by gently 
placing the tail rotor yoke against one flapping stop or trunnion 
stop, allowing full view of the opposite stop. Repeat in opposite 
direction to allow viewing of the opposite stop.
    (2) If either the trunnion stop or flapping stop is deformed or 
bent as shown in Figure 3 or Figure 4, the yoke assembly and 
trunnion stop or flapping stop are no longer serviceable and must be 
replaced with an airworthy yoke assembly that has zero hours TIS or 
has passed x-ray diffraction inspection, and an airworthy flapping 
stop or trunnion stop.

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    (f) Within 30 calendar days after the effective date of this AD, 
insert the following pen and ink changes under the Operating 
Procedures and Maneuvers Pre-Flight Checks section of the Rotorcraft 
Flight Manual or Operational Manual:
    ``Tail rotor yoke--Preflight visual check for static stop 
contact damage (deformed static stop or trunnion yield indicator).''

    Note 5: Operators who use aircraft that have any of these 
affected yoke assemblies installed should use tail rotor tie downs 
when the aircraft is parked or stored.

    (g) 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 Standards Staff, 
Rotorcraft Directorate, 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 Standards Staff.

    Note 6: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Rotorcraft Certification Office.

    (h) 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.
    (i) This amendment becomes effective on May 3, 1999.

    Issued in Fort Worth, Texas, on March 23, 1999.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-7778 Filed 3-31-99; 8:45 am]
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