# AD 74-10-13: Auxiliary Hydraulic System - Type: Airworthiness directive - Status: Current - Products: Boeing 707-100 Long Body, 707-100B Long Body, 707-100B Short Body, 707-200, 707-300 Series, 707-300B Series, 707-300C Series, 707-400 Series, 720 Series and 720B Series - Effective: May 14, 1974 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-1845 - Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/CD7D76BD66BD62CC8625683200549342.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/74-10-13 ## The airworthiness directive 74-10-13 BOEING: Amendment 39-1845. Applies to all Model 707 and 720 airplanes having 6,000 hrs., or more, time in service, certificated in all categories. Compliance is required as indicated, unless already accomplished. To prevent excessive non-recoverable internal hydraulic leakage in the auxiliary hydraulic system and the possible loss of aircraft direction control at critical air speeds, accomplish the following: PART I (a) PART I of this AD applies to airplanes which will be used for flight crew training. (b) Prior to further flight for crew training, and thereafter at intervals not to exceed 2,000 hours time in service from the last inspection, the airplane auxiliary hydraulic system must be inspected and replaced or reworked, as necessary, in accordance with the following: (1) Inspect for evidence of internal leakage per the information contained in Boeing Alert Service Bulletin 3154 dated April 12, 1974, or later FAA approved revisions of Boeing Alert Service Bulletin 3154 or by an equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. (2) Airplanes with an auxiliary hydraulic system having internal leakage equal to or greater than 1.0 GPM but less than 3.0 GPM may not be used in training or revenue service but may only be flown in accordance with FAR 21.197 to a maintenance base for replacement or rework, as necessary, of the defective auxiliary hydraulic system components. (3) Airplanes with an auxiliary hydraulic system having 3.0 GPM, or more, internal leakage must have the defective auxiliary hydraulic system components replaced or overhauled, as necessary, prior to further flight. PART II (a) PART II of this AD applies to airplanes which have not been inspected and reworked, as necessary, in accordance with Amendment 39-1753 (F. R. Doc. 73-25927), AD-73-25-2. (b) Within 300 hours time in service after the effective date of this AD, and thereafter at intervals not to exceed 2,000 hours time in service from the last inspection, accomplish the following: (1) Inspect for evidence of internal leakage and replace or rework, as necessary, per the information contained in Boeing Alert Service Bulletin 3154 dated April 12, 1974, or later FAA approved revisions of Boeing Alert Service Bulletin 3154 or by an equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. (2) Airplanes with an auxiliary hydraulic system having internal leakage equal to or greater than 1.0 GPM but less than 3.0 GPM may not be used in revenue service but may only be flown in accordance with FAR 21.197 to a maintenance base for replacement or rework, as necessary, of the defective auxiliary hydraulic components. (3) Airplanes with an auxiliary hydraulic system having 3.0 GPM, or more, internal leakage must have the defective auxiliary hydraulic system components replaced or overhauled, as necessary, prior to further flight. PART III (a) PART III of this AD applies to airplanes which have been inspected and reworked, as necessary, in accordance with Amendment 39-1753 (F. R. Doc. 73-25927), AD-73-25-2. (b) Within 600 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 2,000 hours time in service from the last inspection, accomplish the following: (1) Inspect for evidence of internal leakage and replace or rework, as necessary, per the information contained in Boeing Alert Service Bulletin 3154 dated April 12, 1974, or later FAA approved revisions of Boeing Alert Service Bulletin 3154, or by an equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. (2) Airplanes with an auxiliary hydraulic system having internal leakage equal to or greater than 1.0 GPM but less than 3.0 GPM, may not be used in revenue service but may only be flown in accordance with FAR 21.197 to a maintenance base for replacement or rework, as necessary, of the defective auxiliary hydraulic system components. (3) Airplanes with an auxiliary hydraulic system having 3.0 GPM, or more, internal leakage must have the defective auxiliary hydraulic system components replaced or overhauled, as necessary, prior to further flight. For the purpose of complying with the repetitive periodic inspection requirement of this AD, the 2,000 hours time in service may be adjusted by submitting substantiating technical data through the FAA assigned maintenance inspector for the approval of the Chief, Engineering and Manufacturing Branch, Flight Standards Division, FAA, Northwest Region. This AD Amendment 39-1845 supersedes AD 73-25-2. This Amendment becomes effective May 14, 1974. ## Affected data sheets (3) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 4A21](https://openairdocs.org/tcds/4A21): The Boeing Company; names 4 of 4 models: 707-100B Short Body, 707-200, 707-100 Long Body, 707-100B Long Body - [TCDS 4A26](https://openairdocs.org/tcds/4A26): The Boeing Company; names 4 of 4 models: 707-300B Series, 707-400 Series, 707-300 Series, 707-300C Series - [TCDS 4A28](https://openairdocs.org/tcds/4A28): The Boeing Company; names 2 of 2 models: 720B Series, 720 Series ## 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: 6 (6 by airframe model, 0 by engine model) - Makers: Boeing 6 Models with the most aircraft: - [Boeing 707-338C](https://openairdocs.org/model/boeing-707-338c): 2 aircraft (airframe model) - [Boeing 707-368C](https://openairdocs.org/model/boeing-707-368c): 1 aircraft (airframe model) - [Boeing 707-321B](https://openairdocs.org/model/boeing-707-321b): 1 aircraft (airframe model) - [Boeing 707-323B](https://openairdocs.org/model/boeing-707-323b): 1 aircraft (airframe model) - [Boeing 707-351B](https://openairdocs.org/model/boeing-707-351b): 1 aircraft (airframe model) All 5 models: https://openairdocs.org/ad/74-10-13/models.md Every aircraft: https://openairdocs.org/ad/74-10-13/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.