{"id":"F2006B10831","name":"AD/INST/29 - Bendix M-4 (A,B,C,D) Automatic Flight Control System Servo - Inspection and Modification","slug":"ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56309,"registerId":"commonwealth-F2006B10831-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/INST/29 - Bendix M-4 (A,B,C,D) Automatic Flight Control System Servo - Inspection and Modification","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png) \nInstruments and Automatic Pilots\n\nAD/INST/29 Bendix M-4 (A,B,C,D) Automatic Flight Control System Servo - Inspection and Modification\n\n \n1/81\n\nApplicability: All Models 3013E, 3013F, 3013G, 3013H, 3013J and 3013K Primary Servos (part numbers and serial numbers listed below) delivered, repaired or overhauled after 1 January 1979 that do not contain Modification Number 4.\n\n```html\n

Primary Servo Model Number

Primary Servo Part Number

Primary Servo Serial Number

*3013E

*3013F

*3013G

1U014-01

1U014-02

1U014-03

Any primary servo that has had magnetic clutches (P/N 717503- 0001) installed after

1 January 1979.

3013H

4000523-8501

9530 thru 9925 and any primary servo that has been repaired or overhauled after 1 January 1979.

3013J

4009506-8501

1775 thru 1792 and any primary servo that has been repaired or overhauled after 1 January 1979.

3013K

4009506-8502

2067 thru 2110 and any primary servo that has been repaired or overhauled after 1 January 1979.

\n```\n\n\\*Older model primary servos which may contain magnetic clutches manufactured by Bendix.\n\nDocument: Bendix Alert SB M-4D-060.\n\nCompliance: Within 100 hours time in service after 31 January 1981.\n\nBackground: Instances have been reported overseas of mechanical seizure of the primary servo motors detailed above. When this condition exists the primary flight controls may be subjected to an increase in required actuation forces which may reach the slipping value of the capstan torque limiters, thus demanding greater effort by the pilot. The seizure may occur whether the autopilot is turned on or off.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive targets a narrow set of Bendix M‑4 primary servos lacking Modification Number 4 and delivered/repaired/overhauled after 1 January 1979. The text sets a specific compliance deadline and references a Bendix alert for corrective work; no broader expansion of scope is indicated in the source material."},"complexity_factors":["Detailed applicability limited to specific servo models, part numbers and serial-number ranges (Applicability table).","Temporal and status condition: applies only to units delivered, repaired or overhauled after 1 January 1979 and lacking Modification Number 4 (Applicability).","Fixed short compliance window: inspection/modification within 100 hours time in service after 31 January 1981 (Compliance).","Technical remediation based on manufacturer document: Bendix Alert SB M-4D-060 referenced as the procedural source (Document).","Safety-critical mechanical failure described (motor seizure raising actuation forces to capstan torque‑limiter slip value) which dictates an operational risk mitigation imperative (Background).","Practical compliance burdens on owners/operators: maintenance cost, parts/repair availability and aircraft downtime to inspect/modify units (implied by Applicability and Compliance)."],"plain_english_summary":"**What it does:** Requires inspection and, where necessary, modification of certain Bendix M‑4 primary servos (models 3013E, 3013F, 3013G, 3013H, 3013J and 3013K and listed part/serial numbers) delivered, repaired or overhauled after 1 January 1979 that do not contain Modification Number 4. \n\n**Who it affects and why it matters:** Applies to aircraft owners, operators and maintenance organisations that have these servos; compliance was required within 100 flight hours after 31 January 1981 because of reported servo‑motor seizures that can increase pilot control forces (autopilot on or off)."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in identified equipment. The scope remains precisely limited to the Bendix M-4 servo seizure issue as originally intended."},"complexity_factors":["Highly technical subject matter (aviation engineering) with specific part numbers and serial number ranges","Tabular data with multiple model variants (3013E through 3013K) requiring cross-referencing","Date-based applicability triggers (delivery/repair/overhaul after 1 January 1979)","Conditional exemption (servos already containing Modification Number 4 are excluded)","Compliance deadline calculated from 'time in service' rather than calendar date","Reference to external technical document (Bendix Alert SB M-4D-060) for actual modification procedures"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and modification of certain Bendix M‑4 automatic flight control servos (models 3013E–3013K) delivered, repaired, or overhauled after 1 Jan 1979 unless already fitted with Modification No. 4. \n\nWork must be done per Bendix Alert SB M‑4D‑060 within 100 flight hours after 31 Jan 1981 to prevent mechanical seizure that can jam or stiffen controls; noncompliance renders the aircraft unairworthy."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification","history":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification/history","analysis":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification/analysis","conflicts":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification/important-cases","documents":"/api/acts/ad-inst-29-bendix-m-4-a-b-c-d-automatic-flight-control-system-servo-inspection-and-modification/documents"}}