Airworthiness Directive · Amendment 39-21549 · Engine/transmission coupling
Carson Helicopters, Inc.; Croman Corporation; Sikorsky Aircraft Corporation; and Siller Helicopters
This AD applies to all helicopters identified in paragraphs (c)(1) through (6) of this AD, certificated in any category including restricted.
(1) Carson Helicopters, Inc., Model S-61L helicopters.
(2) Carson Helicopters, Inc., Model SH-3H helicopters.
(3) Croman Corporation Model SH-3H helicopters.
(4) Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V helicopters.
(5) Siller Helicopters Model CH-3E helicopters.
(6) Siller Helicopters Model SH-3A helicopters.
The FAA is adopting a new airworthiness directive (AD) for all Carson Helicopters, Inc., Model S-61L and SH-3H helicopters; Croman Corporation Model SH-3H helicopters; Sikorsky Aircraft Corporation Model S-61A, S-61D, S-61E, and S-61V helicopters; and Siller Helicopters Model CH-3E and SH-3A helicopters. This AD was prompted by an accident. This AD requires tracking hours time-in-service (TIS) and external lift cycles (lift cycles) for certain main gearbox left and right input freewheel unit (IFWU) assemblies. This AD also requires determining the type of IFWU assembly installed and depending on the results, calculating the moving average, repetitive inspections, recording certain information, replacing parts, and marking parts. The FAA is issuing this AD to address the unsafe condition on these products.
Within 10 hours time-in-service (TIS) after the effective date of this AD, do the actions specified in paragraphs (g)(1) and (2) of this AD.
(1) Create an external lift component history card or equivalent record for each IFWU assembly, part number (P/N) 61074-35000-041 through 61074-35000-063 inclusive.
(2) Count and, at the end of each day's operations, record the number of external lift cycles (lift cycles) performed and the hours TIS for each IFWU assembly, P/N 61074-35000-041 through 61074-35000-063 inclusive. A “lift cycle” is defined as the lifting of an external load and subsequent release of the load. Record the lift cycles and hours TIS on the external lift component history card or equivalent record.
(1) Upon reaching 250 hours TIS after the effective date of this AD on each IFWU assembly, P/N 61074-35000-041 through 61074-35000-063 inclusive, determine whether the IFWU assembly is a repetitive external lift (REL) or non-REL IFWU assembly by using a 250-hour TIS moving average. To perform the calculation, divide the total number of lift cycles performed during the first 250 hours TIS by 250. The result will be the first moving average calculation of lift cycles per hour TIS.
(i) If the calculation specified in paragraph (h)(1) of this AD results in more than 6 lift cycles per hour TIS, the IFWU assembly is an REL IFWU assembly.
(ii) If the calculation specified in paragraph (h)(1) of this AD results in 6 or less lift cycles per hour TIS, the IFWU assembly is a Non-REL IFWU assembly.
(2) For each IFWU assembly determined to be a Non-REL IFWU assembly based on the first calculation of the 250-hour TIS moving average for lift cycles specified in paragraph (h)(1) of this AD: Within 50 hours TIS after the determination, and thereafter at intervals of 50 hours TIS, recalculate the average lift cycles per hour TIS to determine whether the IFWU assembly is an REL or non-REL IFWU assembly. To perform the calculation, subtract the total number of lift cycles performed during the first 50-hour TIS interval used in the previous moving average calculation from the total number of lift cycles performed on the IFWU assembly during the previous 300 hours TIS. Divide this result by 250. The result will be the next or subsequent moving average calculation of lift cycles per hour TIS.
(i) If any calculation specified in paragraph (h)(2) of this AD results in more than 6 lift cycles per hour TIS, the IFWU assembly is an REL IFWU assembly.
(ii) If any calculation specified in paragraph (h)(2) of this AD results in 6 or less lift cycles per hour TIS, the IFWU assembly is a Non-REL IFWU assembly.
Note 1 to paragraph (h)(2): Sikorsky Aircraft Corporation All Operators Letter (AOL) CCS-61-AOL-04-0005, dated May 18, 2004, provides an example and additional information about tracking cycles and the moving average procedure.
Note 2 to paragraph (h)(2): The following is a sample calculation for subsequent 50 hour TIS intervals. Assume the total number of lift cycles for the first 50 hour TIS interval used in the previous moving average calculation = 450 lift cycles and the total number of lift cycles for the previous 300 hours TIS = 2,700 lift cycles. The subsequent moving average of lift cycles per hour TIS = (2,700−450) divided by 250 = 9 lift cycles per hour TIS.
(3) Once an IFWU assembly is determined to be an REL IFWU assembly, it remains an REL IFWU assembly for the rest of its service life and is subject to the inspection for REL IFWU assemblies required by paragraph (i) of this AD.
(4) Once an IFWU assembly is determined to be an REL IFWU assembly, you no longer need to perform the 250-hour TIS moving average calculation required by paragraph (h)(2) of this AD, but you must continue to count and record the lift cycles as required by paragraph (g)(2) of this AD.
For each REL IFWU assembly, as determined by paragraph (h)(1) or (2) of this AD:
(1) Within 500 hours TIS or 7,500 lift cycles, whichever occurs first since the assembly was determined to be a REL IFWU assembly, and thereafter at intervals not to exceed 500 hours TIS or 7,500 lift cycles, whichever occurs first, inspect for wear, surface distress, and endplay by following paragraphs B.(1) through B.(6) of the Accomplishment Instructions of Sikorsky Aircraft Corporation Alert Service Bulletin 61B35-67B, Revision B, dated August 11, 2003. Record all the information specified in Figures 1 through 3 of the Sikorsky Aircraft Corporation Alert Service Bulletin 61B35-67B, Revision B, dated August 11, 2003. You may record this information on any suitable maintenance record, or you may use the Sikorsky evaluation forms provided in Sikorsky Aircraft Corporation Alert Service Bulletin 61B35-67B, Revision B, dated August 11, 2003. This AD does not require you to contact Sikorsky or provide information to Sikorsky.
(2) If during any inspection required by paragraph (i)(1) of this AD, any IFWU assembly part is found whose average wear, wear marks, surface distress, or endplay exceeds the limits specified in paragraphs B.(1) through B.(6) of the Accomplishment Instructions of Sikorsky Aircraft Corporation Alert Service Bulletin 61B35-67B, Revision B, dated August 11, 2003, before further flight, replace the affected part with an airworthy IFWU assembly part.
Note 3 to paragraph (i)(2): Sikorsky Aircraft S-61L/N Overhaul Manual, SA4045-83, Revision 20, dated August 15, 2003, as revised by Temporary Revisions 65-193, -194, -195, and -196, contains the overhaul procedures for the IFWU assembly.
For each REL IFWU assembly, as determined by paragraph (h)(1) or (2) of this AD: Before further flight after the assembly was determined to be an REL IFWU assembly, permanently mark IFWU camshafts, P/N 61350-24052, 61350-24072, S6135-20611, S6135-20614 and S6137-23075, and IFWU gear housings, P/N 61350-24051, 61350-24068, S6135-20695, and S6137-23057, with the letters “REL”. Mark the camshafts by applying etching ink on the surface of the part that is 0.5-inch square with the depth of the letters not to exceed 0.001 inch. Before further flight and after etching, neutralize the etched surface and oil to prevent corrosion.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
