[Federal Register Volume 63, Number 27 (Tuesday, February 10, 1998)]
[Proposed Rules]
[Pages 6685-6689]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-3228]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-SW-60-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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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to Sikorsky Aircraft-manufactured
Model CH-54A helicopters. This proposal would require an initial and
recurring inspections and rework or replacement, if necessary, of the
second stage lower planetary plate (plate). This proposal is prompted
by cracked plates that have been found during overhaul and inspections.
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 April 13, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of Regional Counsel, Southwest Region,
Attention: Rules Docket No. 97-SW-60-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: Mr. Uday Garadi, Aerospace Engineer,
FAA, Rotorcraft Directorate, Rotorcraft Certification Office, Fort
Worth, Texas 76193-0170, telephone (817) 222-5157, fax (817) 222-5959.
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
[[Page 6686]]
statement is made: ``Comments to Docket No. 97-SW-60-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 Regional Counsel, Southwest Region, Attention:
Rules Docket No. 97-SW-60-AD, 2601 Meacham Blvd., Room 663, Fort Worth,
Texas 76137.
Discussion
This notice proposes the adoption of a new AD that is applicable to
Sikorsky-manufactured Model CH-54A helicopters. This proposal would
require an initial and recurring inspections and rework of the plate or
replacement, if necessary. It is believed that cracks on the plate
initiate at and radiate from the lightening holes in the plate web due
to fatigue. This condition, if not corrected, could result in failure
of the main gearbox, failure of the drive system, and subsequent loss
of control of the helicopter.
Since an unsafe condition has been identified that is likely to
exist or develop on other Sikorsky-manufactured Model CH-54A
helicopters of the same type design, the proposed AD would require an
initial and recurring inspections and replacement, if necessary, of the
plate.
The FAA estimates that 9 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 $106,560; $4,320 to
accomplish the inspections and rework, and $102,240 to replace the
plate in the main gearbox assembly in all 9 helicopters, if necessary.
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.
2. Section 39.13 is amended by adding a new airworthiness directive
to read as follows:
Sec. 39.13 [Amended]
Columbia Helicopter; Heavy Lift; Silver Bay Logging: Docket No. 97-
SW-60-AD.
Applicability: 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
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 use the authority
provided in paragraph (d) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition, or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any helicopter from the applicability of this AD.
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.
(2) If no crack is discovered, rework the plate as follows:
(i) Locate the center of each 1.750 inch-diameter lightning 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; two hundred 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 three 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).
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(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.
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(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, re-
identified as P/N 6435-20229-102-TS-107 after rework.
Note 2: Erickson Air-Crane Company Service Bulletin No. 64B35-
7C, dated November 8, 1995 pertains to the subject of this AD.
(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,
FAA, Rotorcraft Directorate. 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 3: 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 February 3, 1998.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 98-3228 Filed 2-9-98; 8:45 am]
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