[Federal Register Volume 65, Number 77 (Thursday, April 20, 2000)]
[Proposed Rules]
[Pages 21159-21164]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-9900]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-81-AD]


Airworthiness Directives; Sikorsky Aircraft-manufactured Model 
CH-54A Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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[[Page 21160]]

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to Sikorsky Aircraft-
manufactured Model CH-54A helicopters, that currently requires initial 
and recurring inspections and rework or replacement, if necessary, of 
the second stage lower planetary plate (plate). This action would 
require the same actions as the existing AD but would add two 
additional type certificate (TC) holders to the applicability of the AD 
and change one TC holder who has transferred ownership of the affected 
helicopters since the issuance of the existing AD. This proposal is 
prompted by the discovery that the applicability section of the 
existing AD is incomplete. The actions specified by the proposed AD are 
intended to prevent failure of the plate due to fatigue cracking which 
could result in failure of the main gearbox, failure of the drive 
system, and subsequent loss of control of the helicopter.

DATES: Comments must be received on or before June 19, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-81-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137. You may also send comments electronically to 
the Rules Docket at the following address: <a href="/cdn-cgi/l/email-protection#192034786a6e34787d7a7674747c776d6a597f7878377e766f"><span class="__cf_email__" data-cfemail="370e1a5644401a565354585a5a525943447751565619505841">[email protected]</span></a>. 
Comments may be inspected at the Office of the Regional Counsel between 
9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Uday Garadi, Aviation Safety Engineer, 
Rotorcraft Standards Staff, Rotorcraft Directorate, FAA, Fort Worth, 
Texas 76193-0110, telephone (817) 222-5123, fax (817) 222-5961.

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 mailed 
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-81-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, Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 99-SW-81-AD, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137.

Discussion

    On March 25, 1999, the FAA issued AD 99-07-16, Amendment 39-11102 
(64 FR 15669, April 1, 1999), to require initial and recurring 
inspections and rework or replacement, if necessary, of the plate. 
Cracks on the plate, part number 6435-20229-102, initiate at and 
radiate from the lightening holes in the plate web due to fatigue. That 
action was prompted by cracked plates that were found during overhaul 
and inspections. The requirements of that AD are intended to prevent 
failure of the plate due to fatigue cracking, which could result in 
failure of the main gearbox, failure of the drive system, and 
subsequent loss of control of the helicopter.
    Since the issuance of that AD, the FAA has discovered that two TC 
holders were inadvertently omitted from the applicability section and 
one TC holder has transferred the TC for an affected model helicopter.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Sikorsky Aircraft-manufactured Model CH-54A 
helicopters of the same type design, the proposed AD would supersede AD 
99-07-16 to require initial and recurring inspections and rework or 
replacement, if necessary, of the plate.
    The FAA estimates that 12 helicopters of U.S. registry would be 
affected by this proposed AD, that it would take approximately 8 work 
hours per helicopter to accomplish the proposed inspections and 56 
hours to remove and replace the plate, and that the average labor rate 
is $60 per work hour. Required parts would cost approximately $8,000 
per helicopter. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators is estimated to be $142,080 to replace 
the plates in the entire fleet.
    The regulations proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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 39-11102 (64 FR 
15669, April 1, 1999), and by adding a new airworthiness directive 
(AD), to read as follows:

Siller Helicopters; Aviation International Rotors, Inc. (Air, Inc); 
Columbia Helicopters, Inc.; Chet Raspberry, Inc. (CRI); Silver Bay 
Logging, Inc.: Docket No. 99-SW-81-AD. Supersedes AD 99-07-16, 
Amendment 39-11102, Docket No. 97-SW-60-AD.


[[Page 21161]]


    Applicability: Model CH-54A helicopters with lower planetary 
plate, part number (P/N) 6435-20229-102, 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 (d) 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 second stage lower planetary plate 
(plate), P/N 6435-20229-102, due to fatigue cracking, which could 
lead to failure of the main gearbox, failure of the drive system, 
and subsequent loss of control of the helicopter, accomplish the 
following:
    (a) On or before accumulating 1,300 hours time-in-service (TIS), 
conduct a fluorescent magnetic particle inspection of the plate, P/N 
6435-20229-102, in the circumferential and longitudinal directions 
using the wet continuous method. Pay particular attention to the 
area around the 9 lightening holes.
    (1) If any crack is discovered, replace the plate with an 
airworthy plate prior to further flight.
    (2) If no crack is discovered, rework the plate as follows:
    (i) Locate the center of each 1.750 inch-diameter lightening 
hole and machine holes 0.015 to 0.020 oversize on a side (0.030 to 
0.040 diameter oversize). Machined surface roughness must not exceed 
63 microinches AA rating (see Figure 1).
    (ii) Radius each hole 0.030 to 0.050 inches on each edge as 
shown in Figure 1.
    (iii) Mask the top and bottom surfaces of the plate to expose 
3.20 inch minimum width circumferential band as shown in Figure 1.
    (iv) Vapor blast or bead exposed surfaces to remove protective 
finish. Use 220 aluminum oxide grit at a pressure of 80 to 90 pounds 
per square inch.
    (v) Shot peen exposed surfaces and inside and edges of 
lightening holes to 0.008-0.012A intensity. Use cast steel shot, 
size 170; 200 percent coverage is required. Use the tracer dye 
inspection method to ensure the required coverage. Also, visually 
inspect the shot peened surfaces for correct shot peen coverage. 
Inspect the intensity of the shot by performing an Almen strip 
height measurement.
    (vi) Clean reworked surfaces using acetone. Touch up the 
reworked areas using Presto Black or an equivalent touchup solution. 
Ensure that the touchup solution is at a temperature between 70  
deg.F to 120  deg.F during use. Keep the reworked surfaces wet with 
touchup solution for 3 minutes to obtain a uniform dark color. Rinse 
and dry the reworked areas.
    (vii) Polish the reworked surfaces with a grade 00 or finer 
steel wool and polish with a soft cloth. Coat the reworked surfaces 
with preservative oil.
    (viii) Identify the reworked plate by adding ``TS-107'' after 
the part number using a low-stress depth-controlled impression-stamp 
with a full fillet depth of not more than 0.003 inch (see Figure 1).
BILLING CODE 4910-13-P

[[Page 21162]]

[GRAPHIC] [TIFF OMITTED] TP20AP00.032


[[Page 21163]]


    (b) For any plate, P/N 6435-20229-102, that has been reworked 
and identified with ``TS-107,'' on or before the accumulation of 
1,500 hours TIS and thereafter at intervals not to exceed 70 hours 
TIS, accomplish the following:
    (1) Inspect the plate for a crack in the area around all nine 
lightening holes using a Borescope or equivalent inspection method 
(see Figure 2).
    (2) If a crack is found, replace the plate with an airworthy 
plate prior to further flight.
[GRAPHIC] [TIFF OMITTED] TP20AP00.033

BILLING CODE 4910-13-C

[[Page 21164]]

    (c) On or before the accumulation of 2,600 hours TIS, remove 
from service plates, P/N 6435-20229-102, reidentified as P/N 6435-
20229-102-TS-107 after rework. This AD revises the airworthiness 
limitation section of the maintenance manual by establishing a 
retirement life of 2,600 hours TIS for the main gearbox assembly 
second stage lower planetary plate, P/N 6435-20229-102, reidentified 
as P/N 6435-20229-102-TS-107 after rework.
    (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, 
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 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 
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 13, 2000.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 00-9900 Filed 4-19-00; 8:45 am]
BILLING CODE 4910-13-P


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