# AD 74-08-01: Autopilot Servo Actuators

- Type: Airworthiness directive
- Status: Current
- Products: Aircraft Radio Autopilot Servo Actuators, 172L, 172M, 177B, 177RG, 180H, 180J, 182N, 182P, 185E, 207, 210K and 20 more
- Effective: April 9, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Appliance
- Amendment: 39-1808
- Registered aircraft: 10,879 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/540107CA6D7CDF7386256A320048CF24.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-08-01

## The airworthiness directive

74-08-01 AIRCRAFT RADIO CORPORATION: Amendment 39-1808. Applies to Aircraft Radio Corporation autopilot servo actuators PA-500A, PA-520A, or PA-520B used in 300 and 400 series Cessna autopilots and 300, 400 and 800 series IFCS. Refer to attached list of those Cessna Model airplanes which may have had these actuators installed at the factory or in the field. Subject actuators may have been installed or used as replacement parts in other aircraft.

Compliance: Required as indicated, unless already accomplished.

To prevent possible jamming of the autopilot actuator due to an internal screw becoming loose and jamming against the internal surface of the actuator case body, accomplish the following:

A) For all aircraft with 300 hours' or less time in service since autopilot installation, within 25 hours' time in service after the effective date of this AD, inspect the autopilot actuators and take action in accordance with Cessna Avionics Service Letter AV74-3 and ARC Service Bulletin No. 171 or later FAA-approved revisions.

B) For all aircraft with more than 300 hours' time in service since autopilot installation, during the next routine, annual, or 100-hour inspection, whichever comes first, inspect the autopilot actuators and take action in accordance with Cessna Avionics Service Letter AV74-3, and ARC Service Bulletin No. 171 or later FAA-approved revisions.

C) Any alternate method of compliance with this AD must be referred to and approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

This amendment becomes effective April 9, 1974.

ATTACHMENT - CESSNA AIRCRAFT MODEL AND SERIAL EFFECTIVITY

MODELS 172L and M - 17259287 thru 63027

MODEL F172K, L, and M - F1720780 thru 1004, 1006 thru 1009, 1012, 1013, 1015 thru 1033, 1035, 1037 thru 1039, 1041 thru 1044, 1046, 1047, 1049, 1050, 1053, 1054, 1056, 1057, 1060, 1062, 1066, 1068, 1070, 1072, 1076, 1079, 1086, 1090, 1091, 1094 thru 1096, 1099, 1102, 1107, 1115

MODEL FR172H - FR1720240 thru 0427, 0429, 0431, 0432, 0434, 0437, 0438, 0440 thru 0445, 0447, 0449, 0450 thru 0452, 0454 thru 0457, 0462

MODEL 177B - 17701576 thru 02077

MODEL 177RG - 177RG0001 thru 0442, 0444 thru 0502

MODEL F177RG - F177RG0001 thru 0095

MODEL 180H & J - 18052170 thru 52429

MODEL 182N & P - 18260460 thru 62493, 62495 thru 62764, 62766 thru 62813, 62815 thru 62840, 62842 thru 62853, 62855 thru 62914

MODEL 185 E and F - 18501815 thru 02376

MODEL P206E - P20600626 thru 00647

MODEL U206 E and F - U20601447 thru 02265, 02267 thru 02290, 02292 thru 02303, 02305 thru 02309, 02311 thru 02333, 02337 thru 02339

MODEL 207 - 20700149 thru 00243

MODEL 210K and L - 21059200 200 thru 60089, 60091 thru 60104, 60106 thru 60155, 60157 thru 60163, 60165 thru 60167, 60169 thru 60171, 60174 thru 60176, 60178 thru 60180, 60182 thru 60184, 60186, 60187, 60189 thru 60193, 60196, 60198, 60201, 60202, 60204 thru 60206, 60208, 60212, 60213, 60215, 60216, 60217, 60227, 60228, 60230, 60232, 60233 thru 60236, 60238 thru 60240

MODEL 310Q - 310Q0001 thru 1027, 1034, 1037

MODEL 337E and F - 33701290 thru 01532, 01534 thru 01567, 01569 thru 01572, 01575 thru 01578, 01579 thru 01581, 01583 thru 01585, 01587 thru 01589, 01592

MODEL F337G - F3370020 thru 0063

MODEL T337G - P3370001 thru 0045, 0047 thru 0065, 0067 thru 0132, 0134 thru 0139, 0142 thru 0147, 0150, 0154, 0155, 0156, 0158, 0159

MODEL FT337G - FP3370001, 0003, 0005, 0008

MODEL 340 - 3400001 thru 0322

MODEL 401B - 401B0001 thru 0221

MODEL 402B - 402B0001 thru 0445, 0447 thru 0508, 0510 thru 0525, 0527 thru 0529, 0531 thru 0547, 0549, 0550, 0552 thru 0558, 0560 thru 0567

MODEL 414 - 4140001 thru 0498

MODEL 421B - 421B0001 thru 0559, 0561 thru 0573, 0576 thru 0579

## Affected data sheets (17) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A7CE](https://openairdocs.org/tcds/A7CE): Textron Aviation Inc.; names 4 of 16 models: 402B, 414, 421B, 401B
- [TCDS A4CE](https://openairdocs.org/tcds/A4CE): Textron Aviation Inc.; names 3 of 29 models: P206E, U206E, U206F
- [TCDS A4EU](https://openairdocs.org/tcds/A4EU): Textron Aviation Inc.; names 3 of 11 models: F172M, F172L, F172K
- [TCDS A6CE](https://openairdocs.org/tcds/A6CE): Textron Aviation Inc.; names 3 of 19 models: 337F, T337G, 337E
- [TCDS 3A12](https://openairdocs.org/tcds/3A12): Textron Aviation Inc.; names 2 of 18 models: 172M, 172L
- [TCDS 3A13](https://openairdocs.org/tcds/3A13): Textron Aviation Inc.; names 2 of 23 models: 182P, 182N
- [TCDS 3A21](https://openairdocs.org/tcds/3A21): Textron Aviation Inc.; names 2 of 28 models: 210L, 210K
- [TCDS 5A6](https://openairdocs.org/tcds/5A6): Textron Aviation Inc.; names 2 of 11 models: 180J, 180H
- [TCDS A23EU](https://openairdocs.org/tcds/A23EU): Textron Aviation Inc.; names 2 of 8 models: F337G, FT337GP
- [TCDS 3A10](https://openairdocs.org/tcds/3A10): Textron Aviation Inc.; names 1 of 23 models: 310Q
- [TCDS 3A24](https://openairdocs.org/tcds/3A24): Textron Aviation Inc.; names 1 of 8 models: 185E
- [TCDS 3A25](https://openairdocs.org/tcds/3A25): Textron Aviation Inc.; names 1 of 11 models: 340
- [TCDS A13CE](https://openairdocs.org/tcds/A13CE): Textron Aviation Inc.; names 1 of 3 models: 177B
- [TCDS A16CE](https://openairdocs.org/tcds/A16CE): Textron Aviation Inc.; names 1 of 4 models: 207
- [TCDS A18EU](https://openairdocs.org/tcds/A18EU): Textron Aviation Inc.; names 1 of 6 models: FR172H
- [TCDS A20CE](https://openairdocs.org/tcds/A20CE): Textron Aviation Inc.; names 1 of 1 models: 177RG
- [TCDS A26EU](https://openairdocs.org/tcds/A26EU): Textron Aviation Inc.; names 1 of 1 models: F177RG

## 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: 10,879 (10,879 by airframe model, 0 by engine model)
- Makers: Cessna 10,875, Reims 3, Reims Aviation S A 1

Models with the most aircraft:

- [Cessna 172M](https://openairdocs.org/model/cessna-172m): 3,573 aircraft (airframe model)
- [Cessna 182P](https://openairdocs.org/model/cessna-182p): 2,099 aircraft (airframe model)
- [Cessna 172L](https://openairdocs.org/model/cessna-172l): 857 aircraft (airframe model)
- [Cessna 177B](https://openairdocs.org/model/cessna-177b): 843 aircraft (airframe model)
- [Cessna 177RG](https://openairdocs.org/model/cessna-177rg): 788 aircraft (airframe model)
- [Cessna 180H](https://openairdocs.org/model/cessna-180h): 366 aircraft (airframe model)
- [Cessna 182N](https://openairdocs.org/model/cessna-182n): 336 aircraft (airframe model)
- [Cessna 310Q](https://openairdocs.org/model/cessna-310q): 277 aircraft (airframe model)
- [Cessna 180J](https://openairdocs.org/model/cessna-180j): 266 aircraft (airframe model)
- [Cessna 414](https://openairdocs.org/model/cessna-414): 242 aircraft (airframe model)
- [Cessna 210L](https://openairdocs.org/model/cessna-210l): 234 aircraft (airframe model)
- [Cessna U206F](https://openairdocs.org/model/cessna-u206f): 230 aircraft (airframe model)
- [Cessna 421B](https://openairdocs.org/model/cessna-421b): 225 aircraft (airframe model)
- [Cessna 340](https://openairdocs.org/model/cessna-340): 164 aircraft (airframe model)
- [Cessna T337G](https://openairdocs.org/model/cessna-t337g): 118 aircraft (airframe model)
- [Cessna 210K](https://openairdocs.org/model/cessna-210k): 50 aircraft (airframe model)
- [Cessna 402B](https://openairdocs.org/model/cessna-402b): 49 aircraft (airframe model)
- [Cessna 207](https://openairdocs.org/model/cessna-207): 40 aircraft (airframe model)
- [Cessna U206E](https://openairdocs.org/model/cessna-u206e): 31 aircraft (airframe model)
- [Cessna 337F](https://openairdocs.org/model/cessna-337f): 24 aircraft (airframe model)

All 33 models: https://openairdocs.org/ad/74-08-01/models.md
Every aircraft: https://openairdocs.org/ad/74-08-01/aircraft.md

Its text cites no advisory circulars or STCs.

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