AD 95-26-08

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.

Final rule; request for comments

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 withinthe 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 OMBcontrol 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 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 thishelicopter 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 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_____ Firefighting____
Utility/Construction_____ 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___.

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. Allcomments 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 ofa 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 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.

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