# AD 71-24-03: Diffuser Case Assembly - Type: Airworthiness directive - Status: Current - Products: Pratt & Whitney Division JT9D-3A - Effective: May 19, 1972 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: 39-1447 - Registered aircraft: 17 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/44FB573B9611690986256E01005AD7D3.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/71-24-03 ## The airworthiness directive 71-24-03 PRATT & WHITNEY ENGINES: Amdt. 39-1335 as amended by Amendment 39-1365 and 39- 1401 is further amended by Amendment 39-1447. Applies to all Pratt & Whitney Aircraft JT9D-3A turbofan engines which incorporate Part Number 669647 diffuser case assembly. Compliance required as indicated. To preclude rupture of the part number 669647 diffuser case assembly as the result of borescope boss weld cracks, accomplish the following: 1. For wet operating JT9D-3A engines with diffuser cases having in excess of 2500 hours or 600 cycles time in service, inspect all borescope positions in accordance with paragraph 4 within 25 cycles after the effective date of this AD and every 25 cycles thereafter. 2. For dry operating JT9D-3A engines with diffuser cases having in excess of 2500 hours or 600 cycles in service, inspect all borescope positions in accordance with paragraph 4 within 100 cycles after the effective date of this AD or 250 cycles since the last inspection, whichever occurs later, and every 250 cycles thereafter. NOTE: For the purposes of this paragraph, JT9D-3A engines operating both wet and dry may be considered as dry operation provided each wet cycle is counted as equivalent to 10 dry cycles. 3. Inspect all borescope positions which have been weld repaired as specified in Pratt & Whitney Aircraft Alert Service Bulletin No. 2901 in accordance with paragraph 4 within the next 5 to 15 cycles after weld repair or 15 cycles after the effective date of this AD, whichever occurs later, and every 25 cycles wet operation or 250 cycles dry operation thereafter. 4. Inspect borescope boss weld areas of the Part Number 669647 diffuser case assembly using one of the techniques specified in Pratt & Whitney Aircraft Alert Service Bulletin No. 2901 or any equivalent inspection procedure approved by the FAA, Chief, Engineering and Manufacturing Branch, Eastern Region. If any crack is found, remove the diffuser case from service, and replaceor repair in accordance with Pratt & Whitney Aircraft Alert Service Bulletin No. 2901. 5. For JT9D-3A engines with diffuser cases incorporating reinforcement straps in accordance with Pratt & Whitney Aircraft Special Instruction No. 29F-71, or equivalent alteration approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, inspect all borescope positions in accordance with paragraph 4 within 250 cycles after installation of the reinforcement straps and every 250 cycles thereafter. 6. Upon submission of substantiating data through an FAA maintenance inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the repetitive inspection times specified in this airworthiness directive. 7. For JT9D-3A engines incorporating fuel nozzle and support assemblies reworked in accordance with Pratt & Whitney Aircraft Turbine Engine Service Bulletin No. 3627 or equivalent method approved by the Chief, Engineering and ManufacturingBranch, Eastern Region, inspect all borescope positions in accordance with paragraph 4 within 75 cycles after installation of the reworked fuel nozzle and support assemblies and every 75 cycles thereafter. NOTE: Turbine Engine Service Bulletin No. 3627 does not apply to engines which incorporate Turbine Engine Service Bulletin No. 3223 or 3628. Amendment 39-1335 was effective November 24, 1971, and was effective upon receipt for all recipients of the telegram dated October 8, 1971 which contained this amendment. Amendment 39-1365 was effective December 31, 1971. Amendment 39-1401 was effective March 14, 1972. This Amendment 39-1447 is effective May 19, 1972. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E20EA](https://openairdocs.org/tcds/E20EA): Pratt & Whitney; names 1 of 9 models: JT9D-3A ## 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: 17 (0 by airframe model, 17 by engine model) - Makers: Boeing 13, Airbus Industrie 2, Douglas 1, Mcdonnell Douglas 1 Models with the most aircraft: - [Pratt & Whitney JT9D series](https://openairdocs.org/engine/pratt-whitney-jt9d-series): 13 aircraft (engine model) - [Pratt & Whitney JT9D-3A](https://openairdocs.org/engine/pratt-whitney-jt9d-3a): 4 aircraft (engine model) All 2 models: https://openairdocs.org/ad/71-24-03/models.md Every aircraft: https://openairdocs.org/ad/71-24-03/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.