[Federal Register Volume 64, Number 73 (Friday, April 16, 1999)]
[Proposed Rules]
[Pages 18835-18840]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9513]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-SW-59-AD]


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to Sikorsky Aircraft-manufactured 
Model CH-54B helicopters. This proposal would require initial and 
recurring inspections and rework or replacement, if necessary, of the 
second stage lower planetary plate (plate). This proposal is prompted 
by two reports of cracked plates that have been found during overhaul 
and inspections. The actions specified by the proposed AD are intended 
to prevent failure of the main gearbox plate due to fatigue cracking, 
which could lead to failure of the main gearbox and subsequent loss of 
control of the helicopter.

DATES: Comments must be received on or before June 15, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Regional Counsel, Southwest Region, 
Attention: Rules Docket No. 97-SW-59-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: 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 statement is made: ``Comments 
to Docket No. 97-SW-59-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. 97-SW-59-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-

[[Page 18836]]

manufactured Model CH-54B helicopters. This proposal would require 
initial and recurring inspections, and rework or replacement, if 
necessary, of the plate. 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 plate due 
to fatigue cracking, which could lead to failure of the main gearbox 
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 Aircraft-manufactured Model CH-54B 
helicopters of the same type design, the proposed AD would require a 
daily inspection of main gearboxes containing a plate with more than 
1,600 hours time-in-service (TIS) for main gearbox oil filter magnesium 
contamination and, if magnesium contamination is discovered, 
replacement of the main gearbox assembly. For main gearbox assemblies 
containing a plate with more than 1,600 hours TIS, this AD also 
requires an inspection of the plate within the next 100 hours TIS after 
the effective date of this AD, and thereafter at intervals not to 
exceed 200 hours TIS, and replacement of the plate if necessary. This 
AD also requires, at the next overhaul of the main gearbox assembly, 
inspection and rework of plates that are not cracked.
    The FAA estimates that 4 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 borescope inspection, 1 work 
hour to inspect the main gearbox oil filter pack, 140 work hours to 
remove and replace the main gearbox assembly, if necessary, and 20 work 
hours to rework 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 $67,760; $2,160 to 
accomplish the initial inspections and $65,600 to replace the plate in 
the main gearbox assembly in all 4 helicopters, if necessary. Daily 
preflight inspections of the main gearbox oil filter pack will cost $60 
per helicopter for each day flight is conducted.
    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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

Blue Bird Helicopters: Docket No. 97-SW-59-AD.

    Applicability: CH-54B helicopters with main gearbox second stage 
lower planetary plate (plate), part number (P/N) 6435-20516-101, 
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 (c) 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 plate due to fatigue cracking, which 
could lead to failure of the main gearbox and subsequent loss of 
control of the helicopter, accomplish the following:
    (a) For main gearbox assemblies containing plate, part number 
(P/N) 6435-20516-101 with 1,600 or more hours time-in-service (TIS):

    Note 2: If the TIS hours of the plate is not known, use the main 
gearbox assembly's total operating time.

    (1) Prior to the first flight of each day, inspect the main oil 
filter for magnesium contamination. If magnesium contamination is 
discovered, replace the main gearbox assembly.
    (2) Within the next 100 hours TIS after the effective date of 
this AD, and thereafter at intervals not to exceed 200 hours TIS, 
conduct a borescope inspection of the plate for cracks in the area 
of the nine lightening holes (see Figure 1). If a crack is found, 
replace the plate with an airworthy plate. The plate, P/N 6435-
20516-101, is part of the main gearbox second stage planetary set 
(P/N 6435-20514-041), which is a serialized matched set, and must be 
replaced as a set.

BILLING CODE 4910-13-P

[[Page 18837]]

[GRAPHIC] [TIFF OMITTED] TP16AP99.009



[[Page 18838]]

    (b) At the next overhaul of the main gearbox assembly, inspect 
and rework the plate, P/N 6435-20516-101, as follows:
    (1) Fluorescent magnetic particle inspect the plate per ASTM 
E1444 in circumferential and longitudinal directions using a wet 
continuous method. Pay particular attention to the area around the 
nine 1.750-inch diameter lightening holes.
    (2) If a crack is found, the plate is unairworthy. Replace it 
with an airworthy plate.
    (3) If no crack is found, rework the plate as follows, ensuring 
that all plate surfaces are free of any crack, scratch, dent, or 
corrosion.
    (i) Measuring from the center of each 1.750-inch diameter 
lightening hole, machine 0.015/0.020 inch from the radius of the 
hole (see Figure 2). Machined surface roughness shall not exceed 63 
microinches AA rating.

[[Page 18839]]

[GRAPHIC] [TIFF OMITTED] TP16AP99.010



BILLING CODE 4910-13-C

[[Page 18840]]

    (ii) Apply a 0.030/0.050-inch radius on the top and bottom edge 
of each hole.
    (4) Fluorescent magnetic particle inspect the reworked areas per 
ASTM E1444 in circumferential and longitudinal directions using a 
wet continuous method.
    (5) If a crack is found, the plate is unairworthy. Replace it 
with an airworthy plate.
    (6) If no crack is found, rework the plate as follows:
    (i) Remove the protective finish from the specified areas on the 
top and bottom of the plate as follows:
    (A) Mask the top and bottom of the plate leaving exposed a 3.20-
inch minimum circumferential band centered on 13.75-inch diameter of 
plate (see Figure 2). Mask the area to protect the thrust washer and 
the surrounding areas from vapor blast.
    (B) Using a vapor blast machine, remove the protective finish 
from the exposed circumferential band on the top and bottom of the 
plate. Use No. 220 aluminum oxide grit at a pressure of 80-90 pounds 
per square inch.
    (ii) Shot peen the specified areas on the plate by remasking the 
top and bottom of the plate leaving exposed the 3.20-inch minimum 
circumferential band centered on 13.75-inch diameter of the plate. 
Mask the area to protect the thrust washer and the surrounding areas 
from the shot peening process.
    (iii) Shot peen the inside diameter of the lightening holes and 
the upper and lower surfaces of the plate in the 3.20-inch minimum 
circumferential band to 0.008 to 0.012A intensity, ensuring 200% 
coverage per MIL-S-13165C or latest revision. Use cast steel shot, 
size 170. Use a tracer dye inspection method.

    Note 3: Overspray is permitted to allow a feathering application 
during the peening process from the peened surface to the non-peened 
surface.

    (iv) Finish the reworked surfaces as follows:
    (A) Clean the surfaces thoroughly with acetone (Fed. Spec O-A-
51, or equivalent).
    (B) Apply Presto black or blueing touchup solution to the 
reworked surfaces with cotton swabs. The solution temperature must 
be between 21 deg. C and 49 deg. C (70 deg. F to 120 deg. F). Keep 
the surfaces wet for about three minutes to get a uniform dark 
color.
    (C) Rinse the surface in cold running water and dry with forced 
air.

    Note 4: A hot water rinse may be used after the cold water rinse 
to speed up drying time.

    (D) Using steel wool, Grade 00 or finer, rub the surfaces 
lightly. Polish with a soft cloth and then coat with a preservative 
oil (MIL-C-15074).
    (v) Identify the reworked plate by stamping the number of this 
AD after the part number. Use a low-stress depth-controlled 
impression-stamp with full fillet depth of no more than 0.003 inch 
(see Figure 2). Marking must be such that it cannot be construed as 
part of the part number.
    (c) 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 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Rotorcraft Certification Office.

    (d) 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 2, 1999.
Larry M. Kelly,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 99-9513 Filed 4-15-99; 8:45 am]
BILLING CODE 4910-13-P