[Federal Register Volume 64, Number 62 (Thursday, April 1, 1999)]
[Rules and Regulations]
[Pages 15669-15673]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-7978]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-60-AD; Amendment 39-11102; AD 99-07-16]
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 adopts a new airworthiness directive (AD), 
applicable to Sikorsky Aircraft-manufactured Model CH-54A helicopters, 
that requires an initial and recurring inspections and rework or 
replacement, if necessary, of the second stage lower planetary plate 
(plate). This amendment is prompted by cracked plates that have been 
found during overhaul and inspections. 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: May 6, 1999.

FOR FURTHER INFORMATION CONTACT: 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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to Sikorsky Aircraft-manufactured 
Model CH-54A helicopters was published in the Federal Register on 
February 10, 1998 (63 FR 6685). That action proposed to require an 
initial and recurring inspections and rework or replacement, if 
necessary, of the plate. It is believed that cracks on the plate, part 
number 6435-20229-102, initiate at and radiate from the lightening 
holes in the plate web due to fatigue.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comment received.
    The sole commenter states that the inclusion of an Erickson Air-
Crane Company Service Bulletin (SB) in the Compliance Section of the AD 
should be removed. The commenter states that the FAA does not have the 
authority to utilize Erickson Air-Crane Company documentation for 
continued airworthiness of CH-54A model helicopters or any other 
helicopters other than Erickson Air-Crane S-64E helicopters. The FAA 
concurs with the comment to the extent that the Erickson Air-Crane SB 
only applies to the Erickson Air-Crane Company Model S-64E series 
helicopters. However, Note 2 of the Notice of Proposed Rulemaking 
(NPRM) only stated that the Erickson Air-Crane SB pertained to the same 
subject as is addressed by the FAA in this rule. It was not 
incorporated by reference into the compliance procedures proposed by 
the NPRM. However, to avoid any confusion as to the model 
applicability, the FAA has deleted proposed Note 2 relating to the 
Erickson Air-Crane Company SB because the note is unnecessary. Also, 
the wording of Note 1 has changed from that published in the NPRM.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. 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 9 helicopters of U.S. registry will be 
affected by this AD, that it will 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 will 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 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.
    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:

[[Page 15670]]

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 99-07-16  Columbia Helicopter; Heavy Lift; Silver Bay Logging: 
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.
    (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 15671]]

[GRAPHIC] [TIFF OMITTED] TR01AP99.000



[[Page 15672]]

    (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.

[GRAPHIC] [TIFF OMITTED] TR01AP99.001


BILLING CODE 4910-13-C

[[Page 15673]]

    (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, 
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 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 May 6, 1999.

    Issued in Fort Worth, Texas, on March 25, 1999.
Mark R. Schilling,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-7978 Filed 3-31-99; 8:45 am]
BILLING CODE 4910-13-P