AD 00-23583

[Federal Register Volume 65, Number 179 (Thursday, September 14, 2000)]
[Rules and Regulations]
[Pages 55453-55457]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-23583]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-SW-81-AD; Amendment 39-11901; AD 2000-18-14]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD) that applies to Sikorsky Aircraft-manufactured Model CH-54A 
helicopters. That AD currently requires initial and recurring 
inspections and rework or replacement, if necessary, of the second 
stage lower planetary plate (plate). This AD requires 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 amendment is prompted by the discovery that the 
applicability section of the existing AD is incomplete. The actions 
specified by this 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.

EFFECTIVE DATE: October 19, 2000.

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

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 99-07-16, 
Amendment 39-11102 (64 FR 15669, April 1, 1999), which applies to 
Sikorsky Aircraft-manufactured Model CH-54A helicopters, was published 
in the Federal Register on April 20, 2000 (65 FR 21159). That action 
proposed to require initial and recurring inspections and rework or 
replacement, if necessary, of the plate.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    The sole commenter indicates that the cost figures utilized in the 
economic analysis are incorrect. The FAA agrees; therefore, the 
approximate cost of procuring a new plate assembly is revised to 
$37,333. The total cost impact of the AD is estimated to be $507,360 to 
replace the plate assemblies in the entire fleet, if necessary.
    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 for the 
change in the economic analysis.
    The FAA estimates that 12 helicopters of U.S. registry will be 
affected by this AD. It will take approximately 8 work hours per 
helicopter to accomplish the inspection; 24 work hours per

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helicopter to remove and rework the assembly; and 56 work hours to 
remove and replace the assembly from each helicopter, if necessary. 
Required parts, if an assembly needs to be replaced, will cost 
approximately $37,333. Based on these figures, the total cost impact of 
the AD on U.S. operators is estimated to be $511,356 ($42,613 per 
helicopter, assuming inspecting the plate once, reworking the assembly 
once, and replacing the assembly).
    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.

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 39-11102 (64 FR 
15669, April 1, 1999), and by adding a new airworthiness directive 
(AD), Amendment 39-11901, to read as follows:

2000-18-14   Siller Helicopters; Aviation International Rotors, Inc. 
(AIR, INC); Columbia Helicopters, Inc.; Chet Raspberry, Inc. (CRI); 
Silver Bay Logging, Inc.: Amendment 39-11901. Docket No. 99-SW-81-
AD. Supersedes AD 99-07-16, Amendment 39-11102, Docket No. 97-SW-60-
AD.

    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).

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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 prior to further flight.
[GRAPHIC] [TIFF OMITTED] TR14SE00.015

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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, 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.
    (f) This amendment becomes effective on October 19, 2000.


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    Issued in Fort Worth, Texas, on September 5, 2000.
Henry A. Armstrong,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 00-23583 Filed 9-13-00; 8:45 am]
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