[Federal Register Volume 60, Number 244 (Wednesday, December 20, 1995)]
[Rules and Regulations]
[Pages 65519-65521]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30772]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-SW-21-AD; Amendment 39-9466; AD 95-26-08]


Airworthiness Directives; Sikorsky Aircraft Model S-58A, S-58B, 
S-58C, S-58D, S-58E, S-58F, S-58G, S-58H, S-58J, S-58BT, S-58DT, S-
58ET, S-58FT, S-58HT, and S-58JT Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Sikorsky Aircraft Model S-58A, S-58B, S-58C, S-58D, S-
58E, S-58F, S-58G, S-58H, S-58J, S-58BT, S-58DT, S-58ET, S-58FT, S-
58HT, and S-58JT helicopters. This action requires initial and 
repetitive magnetic particle inspections of the main rotor shaft 
(shaft) for cracks, and defines power limitations for certain 
helicopter operations. This amendment is prompted by a recent accident 
in which a shaft failed, resulting in loss of power. Subsequent 
inspections on other aircraft of the same type revealed cracks in four 
additional shafts. The actions specified in this AD are intended to 
prevent failure of the shaft, loss of power to the rotor system, and 
subsequent loss of control of the helicopter.

DATES: Effective January 4, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before February 20, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 95-SW-21-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.

FOR FURTHER INFORMATION CONTACT: Mr. Francis X. Walsh, Aerospace 
Engineer, FAA, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, Massachusetts 01803-5299, telephone (617) 
238-7158, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to Sikorsky Aircraft Model S-58A, S-58B, S-58C, S-58D, S-
58E, S-58F, S-58G, S-58H, S-58J, S-58BT, S-58DT, S-58ET, S-58FT, S-
58HT, and S-58JT helicopters with shaft assembly, part number (P/N) 
S1635-20059-2, installed. This AD is prompted by an accident in which 
the failure of a shaft resulted in the crash of a helicopter. Since 
that accident, inspections have revealed cracks in four additional 
shafts. The shaft transmits power to the main rotor system to provide 
lift for the helicopter. Failure of this shaft results in loss of power 
to the main rotor system and subsequent loss of control of the 
helicopter. Due to the criticality of the shaft, this AD must be issued 
immediately to correct an unsafe condition in the affected helicopters.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Sikorsky Aircraft Model S-58A, S-58B, S-58C, 
S-58D, S-58E, S-58F, S-58G, S-58H, S-58J, S-58BT, S-58DT, S-58ET, S-
58FT, S-58HT, and S-58JT helicopters of the same type design, this AD 
is being issued to prevent failure of the shaft, loss of power to the 
rotor system, and subsequent loss of control of the helicopter. This AD 
requires determining the operational cycles-per-hour on the 
helicopters, removing the shaft assembly from the main gear box, and 
inspecting the shaft for cracks using a magnetic particle inspection 
method within the next 50 hours time-in-service (TIS). Following this 
initial inspection, repetitive magnetic particle inspections are 
required. Additionally, this AD prescribes operating limitations for 
certain helicopter operations.-
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 95-SW-21-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant 

[[Page 65520]]
regulatory action'' under Executive Order 12866. It has been determined 
further that this action involves an emergency regulation under DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If 
it is determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from 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.

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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

AD 95-26-08 Sikorsky Aircraft: Amendment 39-9466. Docket No. 95-SW-
21-AD.

    Applicability: Model S-58A, S-58B, S-58C, S-58D, S-58E, S-58F, 
S-58G, S-58H, S-58J, S-58BT, S-58DT, S-58ET, S-58FT, S-58HT, and S-
58JT helicopters with main rotor shaft assembly (shaft assembly), 
part number (P/N) S1635-20059-2, installed, certificated in any 
category.

    Note 1: The shaft assembly consists of a main rotor shaft, P/N 
S1635-20059; an upper end plug, P/N S1635-20153; and a lower end 
plug, P/N S1635-20154. The shaft assembly P/N (S1635-20059-2) is 
marked on the edge of the main rotor shaft lower flange.
    Note 2: 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 (j) 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 main rotor shaft (shaft) loss of power 
to the rotor system, and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) From available helicopter records, determine the maximum 
number of actual operational cycles-per-hour of the current shaft 
assembly since installation. An operational cycle is defined as one 
turnaround (external lift cycle) for external load operations, and 
as one takeoff and one landing for internal load operations. A 
turnaround is defined as picking up an external load, transporting 
that load to a drop-off point, releasing the load, and flying to the 
next load pickup point. If the maximum number of actual operational 
cycles-per-hour cannot be determined, use 25-operational cycles-per-
hour as the maximum operational cycles-per-hour for purposes of this 
AD. Record the determined number of operational usage cycles-per-
hour of the shaft assembly in the appropriate aircraft maintenance 
records.
    (1) If the maximum operational cycles-per-hour has ever equaled 
or exceeded 20 cycles-per-hour, inspect in accordance with paragraph 
(b) of this AD within the next 50 hours time-in-service (TIS), 
unless previously accomplished within the last 200 hours TIS.
    (2) If the maximum operational cycles-per-hour has never 
exceeded 19 cycles-per-hour, inspect the shaft in accordance with 
paragraph (b) of this AD within the next 50 hours TIS, unless 
previously accomplished.
    (b) Remove the shaft assembly, P/N S1635-20059-2, from the main 
gear box. Remove the upper end plug, P/N S1635-20153 and lower end 
plug, P/N S1635-20154, from the shaft assembly, and conduct a 
magnetic particle inspection (MPI) of the shaft for cracks in 
accordance with MIL-STD-1949 or ASTM E-1444. Pay particular 
attention to the inside diameter of the 0.7515-0.7510-inch diameter 
dowel pin holes in the flange and adjacent flange surfaces.

    Note 3: Section 2D of Sikorsky Aircraft Alert Service Bulletin 
58B35-34, dated June 9, 1995, contains a procedure for conducting a 
MPI of the shaft (in agreement with MIL-STD-1949 or ASTM E-1444).

    (c) Conduct repetitive MPI's of the shaft for cracks as follows:
    (1) If the maximum operational cycles-per-hour has ever equaled 
or exceeded 20 cycles-per-hour, repeat the MPI at intervals not to 
exceed 250 hours TIS from the date of the last inspection.
    (2) If the maximum operational cycles-per-hour exceeds 6 cycles-
per-hour, but has always been less than 20 cycles-per-hour, repeat 
the MPI at 1,250 hours TIS, and thereafter at intervals not to 
exceed 250 hours TIS from the date of the last inspection. If the 
last inspection was accomplished between 1,000 hours TIS and 1,250 
hours TIS, begin the repetitive inspections within 250 hours TIS 
from the date of the last inspection instead of at 1,250 hours TIS.
    (3) If the maximum operational cycles-per-hour has never 
exceeded 6 cycles-per-hour, repeat the MPI at 1,250 hours TIS. If 
the last inspection was accomplished between 1,000 hours TIS and 
1,250 hours TIS, repeat the MPI within 250 hours TIS from the date 
of the last inspection instead of at 1,250 hours TIS.
    (d) Report all inspection results to the Manager, Boston 
Aircraft Certification Office, using the Attachment provided later 
in this AD. Reporting requirements have been approved by the Office 
of Management and Budget and assigned OMB control number 2120-0056.
    (e) If no crack is discovered, replace the upper and lower end 
plugs and reinstall the shaft assembly into the main gearbox.
    (f) If any crack is discovered or on or before the shaft 
assembly reaches 2,500 hours TIS, replace the shaft assembly with an 
airworthy shaft assembly, P/N S1635-20059-2. If the replacement 
shaft has previously been in service, determine the maximum 
operational cycles-per-hour in accordance with paragraph (a) and 
inspect in accordance with this AD.

    Note 4: In accordance with the applicable maintenance manual, 
2,500 hours TIS is the mandatory retirement life for the shaft 
assembly, P/N S1635-20059-2.

    (g) If the main rotor shaft assembly installed on the helicopter 
has ever equaled or exceeded 20 or more operational cycles-per-hour, 
insert the following restrictions into the Limitations section of 
the Rotorcraft Flight Manual:
    (1) For turbine engine installations: ``The main rotor shaft 
assembly installed on this helicopter has been operated at 20 or 
more cycles-per-hour. Engine power is restricted to maximum 
continuous power at 93%Nf. Takeoff power operations are 
prohibited.''
    (2) For reciprocating engine installations: ``The main rotor 
shaft assembly installed on this helicopter has been operated at 20 
or more cycles-per-hour. Engine power is restricted to maximum 
continuous power at 2,500 RPM. Takeoff power operations are 
prohibited.''
    (h) If the main rotor shaft assembly installed on the helicopter 
has ever equaled or exceeded 20 or more operational cycles-per-hour, 
install on the instrument panel, adjacent to the pilot's engine 
(Nf or RPM) tachometer, torquemeter, or manifold pressure 
gauges, a placard made of material that is not easily erased, 
disfigured, or obscured that contains the following statement in 
lettering of 0.2 inch minimum height and stated in one or two lines:
    (1) For turbine engine installations: ``MAX PWR: 101% Q AT 93% 
Nf''
    (2) For reciprocating engine installations: ``MAX PWR: 47.5 IN. 
HG at 2,500 RPM''
    (i) Continue to record operational cycles-per-hour of the shaft 
assembly in the appropriate maintenance records. If operational 
cycles-per-hour increases on an affected shaft assembly to the 
extent that it places the shaft assembly into a higher cycles-per-
hour usage group, the applicable requirements and limitations 
contained in this AD for the higher usage group apply to that shaft 
assembly. A replacement shaft assembly must comply with all 
requirements 

[[Page 65521]]
and limitations of this AD as applicable. If the number of operational 
cycles-per-hour determined for a replacement shaft assembly does not 
equal or exceed 20 cycles-per-hour, the Rotorcraft Flight Manual 
limitation specified in paragraph (g) and the placard specified in 
paragraph (h) may be removed.
    (j) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used when approved by the Manager, Boston Aircraft Certification 
Office, FAA, New England Region. Operators shall submit their 
requests through an FAA Principal Maintenance Inspector, who may 
concur or comment and then send it to the Manager, Boston Aircraft 
Certification Office.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Boston Aircraft Certification Office.

    (k) 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.
    (l) This amendment becomes effective on January 4, 1996.

Attachment--Inspection Results Report

    The following information must be reported as soon as possible, but 
no later than 7 days after inspection, to: Manager, Boston Aircraft 
Certification Office, Engine and Propeller Directorate, Aircraft 
Certification Service, Federal Aviation Administration, 12 New England 
Executive Park, Burlington, MA 01803-5299, FAX: (617) 238-7199.

Operator/Repair Station __________
Aircraft Model No. __________
Aircraft Serial No. __________
Date of Inspection __________
Main Rotor Part No. __________
Main Rotor Serial No. __________
Type of Aircraft Utilization:
    Passenger Carry __________
    Utility/Construction __________
    Firefighting __________
    Logging __________
    Other __________
Identify Operational Usage Cycles-Per-Hour:
    1-6 Operational Cycles-Per-Hour __________
    7-19 Operational Cycles-Per-Hour __________
    20-Above Operational Cycles-Per-Hour __________
Next Inspection Date (Estimated): __________
and Flight Hours (Estimated): __________
Magnetic Particle Inspection (MPI) Results (this inspection):
    Passed __________ Failed __________
If a crack is found, indicate the approximate location on the part and 
the length of the crack in inches: ____________
Total Time-In-Service (TIS) (Hours):
    Estimated __________
    Actual __________
    Unknown __________
    At Retirement __________
Inspection results at retirement (if known):
    MPI Passed __________
    Failed __________
    Visual Passed __________
    Failed __________
Log Book Entry for Part No. __________, Serial No. __________, is 
(date) __________, at Retirement Hours __________. This part's Serial 
No. has been marked unairworthy and unfit for further service on (date) 
__________, 199 ____.

    Issued in Fort Worth, Texas, on December 13, 1995.
Daniel P. Salvano,
Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-30772 Filed 12-19-95; 8:45 am]
BILLING CODE 4910-13-U