{"id":"F2008L00252","name":"AD/INST/55 - Garmin GSM 85 Servo Gearbox","slug":"ad-inst-55-garmin-gsm-85-servo-gearbox","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72481,"registerId":"commonwealth-F2008L00252-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Instruments and Automatic Pilots","sectionType":"division","heading":"Instruments and Automatic Pilots","content":"### Instruments and Automatic Pilots\n\n| AD/INST/55 | Garmin GSM 85 Servo Gearbox | 3/2008 DM |\n| ---------- | --------------------------- | --------- |\n\n| Applicability: | All aircraft fitted with GARMIN GSM 85 servo gearbox units, part number (P/N): 011-00894-00, 011-00894-02, 011-00894-04, 011-00894-06, 011-00894-07,011-00894-08, 011-00894-09, 011-00894-10, 011-00894-11 and 011-00894-14.Note 1: GSM 85 servo gearbox units are known to be installed in, but not limited to, the following aeroplanes.(i) Cessna Aircraft Company 182T, T182T, 206H, and T206H(ii) Hawker Beechcraft Corporation G36 and G58(iii) Diamond Aircraft Industries GmbH DA40 and DA40F(iv) Columbia Aircraft Manufacturing 350 and 400(v) Mooney Airplane Company, Inc. M20M and M20R |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Check the serial tag of the installed GSM 85 servo gearbox unit to determine the modification level. The modification (mod) level marked on the serial tag indicates if the GSM 85 servo gearbox unit is already in compliance with this AD.(a) If the serial tag on the installed GSM 85 servo gearbox unit for P/Ns011-00894-00 or 011-00894-10 is marked at mod level 3, no further action is required.(b) If the serial tag on the installed GSM 85 servo gearbox unit for P/Ns011-00894-02, 011-00894-04, 011-00894-06, 011-00894-07, 011-00894-08, 011-00894-09, 011-00894-11, or 011-00894-14 is marked at mod level 1, no further action is required.(c) If the serial tag on the above GSM servo gearbox units is not at mod level 1 or 3 as specified in Requirement (1)(a) and (1)(b) above, then inspect the servo gearbox for foreign object debris in accordance with any of the Service Bulletins listed in Table 1. |\n\n```html\n

2. If foreign object debris is found during the inspection required in Para 1(c), remove and return the GSM 85 servo gearbox to the manufacturer for replacement in accordance with any of the Service Bulletins listed in Table 1, as applicable.

Table 1.

Manufacturer

Service Bulletin No.

Date

Garmin International Inc.

0713 Revision A

07 May 2007

0713 Revision B

18 May 2007

0713 Revision C

29 May 2007

0713 Revision D

13 June 2007

Cessna Aircraft Company

Single Engine Service Bulletin SB07-22-01

04 June 2007

Note 2: FAA AD 2008-02-06; Amendment 39-15336, dated 11 January 2008 refers.

Compliance:

For Requirement 1: Within the next 100 hours time-in-service (TIS) or within the next 3 months after the effective date of this AD, whichever occurs first.

For Requirement 2: Before further flight after the Requirement 1 inspection.

This Airworthiness Directive becomes effective on 26 February 2008.

Background:

This AD results from reports of certain GARMIN GSM 85 servo gearbox units that have foreign object debris inside the assembly. This AD is issued to detect and correct defective GARMIN GSM 85 servo gearbox units, which could result in jamming of the servo gearbox. This jamming could lead to the pilot having to apply sufficient control force to override the servo gearbox slip clutch in order to control the aeroplane. In certain situations, this could compromise the safety of the aeroplane if the pilot was not able to focus on critical duties due to having to tend to the servo gearbox.

\n```\n\n![](image.001.png) \nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n29 January 2008","sortOrder":0},{"sectionNumber":"AD/INST/55","sectionType":"part","heading":"AD/INST/55","content":"## AD/INST/55","sortOrder":1},{"sectionNumber":"Garmin GSM 85 Servo Gearbox","sectionType":"part","heading":"Garmin GSM 85 Servo Gearbox","content":"## Garmin GSM 85 Servo Gearbox","sortOrder":2},{"sectionNumber":"3/2008 DM","sectionType":"part","heading":"3/2008 DM","content":"## 3/2008 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive is narrowly targeted: it applies only to aircraft fitted with the listed Garmin GSM 85 P/Ns and only to units whose serial tag is not at the specified mod levels. It does not require action where the unit’s tag already shows the designated mod level, and the measures are limited to inspection and removal/return if debris is found (see Applicability; Requirement 1(a)-(c); Requirement 2)."},"complexity_factors":["Identification of applicable units by part number and serial-tagged modification level (Requirement 1(a)-(c); Applicability).","Reference to multiple service bulletin revisions and different manufacturers (Table 1: Garmin SB 0713 Rev A–D; Cessna SB07-22-01).","Two-step requirement flow: tag check → conditional inspection → mandatory removal/return if debris found (Requirements 1 and 2).","Short compliance window for initial inspection (within 100 hours TIS or 3 months) and immediate grounding if debris is found (Compliance).","Operational impact on a wide range of aircraft types that use the listed P/Ns (Applicability) leading to potential downtime and coordination with manufacturer for replacement.","Cross-reference to FAA AD 2008-02-06 (Note 2) which may affect interpretation or coordination with overseas directives."],"plain_english_summary":"This Airworthiness Directive requires operators of aircraft fitted with Garmin GSM 85 servo gearbox units (specified part numbers) to check each unit’s serial-tagged modification level and, if not at the required level, inspect the gearbox for foreign-object debris per the listed service bulletins and, if debris is found, remove and return the unit to the manufacturer for replacement. Inspections must occur within 100 flight hours or 3 months and aircraft cannot fly after a debris finding until the unit is replaced, so owners/operators bear inspection, removal, replacement costs and potential downtime."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard targeted Airworthiness Directive addressing a specific safety defect in a specific component. The scope remains tightly focused on the Garmin GSM 85 servo gearbox foreign object debris issue as originally identified."},"complexity_factors":["Multiple part numbers (10 different P/Ns) with different modification level thresholds (mod level 3 vs mod level 1)","Conditional logic: three-branch decision tree (compliant mod level / inspect / no action)","Cross-reference to external documents: 5 different Service Bulletin versions from 2 manufacturers must be consulted","Nested compliance deadlines: primary deadline (100 hours/3 months) vs immediate grounding requirement if debris found","Technical aviation terminology requiring domain knowledge (TIS - time-in-service, mod levels, servo gearbox, slip clutch)"],"plain_english_summary":"This AD mandates inspection of Garmin GSM 85 servo gearboxes (specific part numbers) for foreign object debris that could cause jamming. It affects owners/operators of aircraft fitted with those units (e.g., Cessna 182/206, Beech G36/G58, Diamond DA40, Columbia 350/400, Mooney M20M/M20R).\n\nInspections must be done within 100 flight hours or 3 months; if debris is found the unit must be removed and returned to the manufacturer before next flight."}},"importantCases":[],"_links":{"self":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox","history":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox/history","analysis":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox/analysis","conflicts":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox/conflicts","importantCases":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox/important-cases","documents":"/api/acts/ad-inst-55-garmin-gsm-85-servo-gearbox/documents"}}