# AD 92-09-05: Torque Adapter - Type: Airworthiness directive - Status: Current - Products: Bell Helicopter Textron 212 and 412 - Effective: June 2, 1992 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-8230 - Docket: 91-ASW-31 - Registered aircraft: 70 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/BE4D6A542F358CFE86256A4D0071EE89.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/92-09-05 ## The airworthiness directive 92-09-05 BELL HELICOPTER TEXTRON, INC.: Amendment 39-8230. Docket No. 91-ASW-31. Applicability: Model 212 helicopters, serial numbers (S/N) 35001 through 35037, 35039, and 35040; and Model 412 helicopters, S/N 36001 through 36025, and 36027, certificated in any category. Compliance: Required as indicated, unless previously accomplished. To prevent possible failure of the combining gearbox, which could result in loss of power to the main rotor system, accomplish the following: (a) Within the next 20 hours' time in service after the effective date of this AD, perform an inspection of the torque on the engine-to-driveshaft coupling adapter retaining nut, part number (P/N) 212-040-631-001, as follows: (1) Remove the engine-to-transmission driveshaft in accordance with the appropriate Bell Helicopter Textron, Inc. Maintenance Manual, being careful not to remove the driveshaft adapter assembly. (2) Check the torque of the engine-to-driveshaft adapter retaining nut (see Figure 1). (i) If the retaining nut rotates before attaining 125 foot-pounds of torque (check torque in locking direction) comply with the remaining portion of this AD. (ii) If the retaining nut does not rotate before attaining 125 foot-pounds of torque, no further action is required except to reinstall the engine-to-transmission driveshaft in accordance with the appropriate Bell Helicopter Maintenance Manual. (b) Remove the engine-to-driveshaft coupling adapter in accordance with the appropriate Bell Helicopter Component Repair and Overhaul Manual for the Model 212 or the appropriate Bell Helicopter Maintenance Manual for the Model 412, and inspect the adapter as follows: (1) Check the adapter splines (see Figure 1) for evidence of corrosion fretting. Red dust is an indication of fretting. If fretting is indicated, replace the adapter with a serviceable part before further flight and accomplish the requirements of paragraphs (c) and (d) of this AD. (2) Measure the internal splines of the adapter for a maximum dimension between pins of 1.6632 inches. Use 0.1080 inch diameter pins flatted on one side to 0.1040 inches. If the maximum dimension between pins exceeds 1.6632 inches, replace the adapter with a serviceable part prior to further flight and accomplish the requirements of paragraphs (c) and (d) of this AD. (c) Inspect the engine output drive splines as follows: (1) Inspect the engine output drive splines for evidence of corrosion fretting. Red dust is an indication of corrosion fretting. If fretting is indicated, overhaul the combining gearbox in accordance with the appropriate Pratt and Whitney overhaul manual. (2) Measure the engine output splines for a minimum dimension of 1.9565 inches over pins. Use 0.1080 inch diameter pins. If the minimum dimensions over pins is less than 1.9565 inches, overhaul the combining gearbox in accordance with the appropriate Pratt and Whitney overhaul manual. (d) Install the engine-to-driveshaft coupling adapter as follows (see Figure 1): (1) Position the adapter on the engine. (2) Install the new lock washer. Ensure that the mating face of the lock washer to the adapter is dry. No lubricant is to be used. (3) Lubricate the threads and mating face of the retaining nut (Item number 5 of Figure 1) to the lock washer using grease MIL-G-25537 or MIL-G-81322. (4) Install the retaining nut hand tight. Using a suitable marker, mark an index line on the outer lock washer tang and adapter. This will enable verification that the lock washer does not rotate during torquing operation. (5) Position the plate on the adapter. Install the nut (Item number 4 of Figure 1). Position the bar in the retaining nut. (6) Torque the retaining nut to 250 to 275 foot-pounds (339 to 373 newton-meters) for initial torque. Loosen the retaining nut and then torque 125 to 200 foot-pounds (170-271 newton-meters). (7) Remove the bar and the plate. (8) Inspect the washer to ensure that the tang indexed in paragraph (d)(4) has not rotated. If the inspection reveals that the washer has rotated, repeat the work of paragraphs (d)(2) through (d)(8) using a new lock washer. (9) Bend one tang of the washer into the retaining nut. (10) Install the engine-to-transmission driveshaft in accordance with the appropriate Bell Helicopter Maintenance Manual. (e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished. (f) Compliance with Bell Helicopter Textron, Inc. Alert Service Bulletin No. 212-91-67, dated 6/24/91, for the Model 212 helicopter, or Alert Service Bulletin No. 412-91-53, dated 6/24/91, for the Model 412 helicopter, constitutes compliance with this AD. (g) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used if approved by the Manager, Rotorcraft Certification Office, ASW-170, Rotorcraft Directorate, Aircraft Certification Service, FAA, Southwest Region, 4400 Blue Mound Road, Fort Worth, Texas, 76193-0170. The request shall be forwarded through an FAA inspector who may concur or comment and then send it to the Manager of the Rotorcraft Certification Office. (h) This amendment becomes effective June 2, 1992. NOTES: 1. Install T101588-5 plate (7) on adapter (1). Secure with nut (4). 2. Insert extension bar (6) into plate (7). Ensure that extension bar (6) is seated all the way into nut (5) before attempting to loosen nut (5). 3 Install T103063 plate (7) on adapter (1) for model 412 S/N 36020 and sub. FIGURE 1 AD 92-09-05 ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H4SW](https://openairdocs.org/tcds/H4SW): Bell Textron Inc.; names 2 of 4 models: 212, 412 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 70 (70 by airframe model, 0 by engine model) - Makers: Bell 65, Bell Helicopter Textron 5 Models with the most aircraft: - [Bell 212](https://openairdocs.org/model/bell-212): 54 aircraft (airframe model) - [Bell 412](https://openairdocs.org/model/bell-412): 11 aircraft (airframe model) - [Bell Helicopter Textron 212](https://openairdocs.org/model/bell-helicopter-textron-212): 5 aircraft (airframe model) All 3 models: https://openairdocs.org/ad/92-09-05/models.md Every aircraft: https://openairdocs.org/ad/92-09-05/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.