# AD 94-14-12: Octane Aviation Gasoline

- Type: Airworthiness directive
- Status: Historical
- Products: Teledyne Continental Motors A-65-8, C85-12, E185-11, GO-300-A, GO-300-B, GO-300-C, GO-300-D, GO-300-E, GO-300-F, GTSIO-520-C, GTSIO-520-D, GTSIO-520-E and 59 more
- Issued: June 23, 1994
- Superseded by: [AD 95-21-15](https://openairdocs.org/ad/95-21-15)
- Product type: Engine
- Docket: 94-ANE-33
- Registered aircraft: 70,734 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/54779474A4368ECD86256CC5005C58CB.0001
- DRS record last changed: August 7, 2025
- Page: https://openairdocs.org/ad/94-14-12

## The airworthiness directive

94-14-12 Teledyne Continental Motors: Priority Letter issued on June 23, 1994. Docket No. 94-ANE-33.

Applicability: Teledyne Continental Motors (TCM) A-65-8, C-85-12, E-185-11, E-225-B, O-200, O-300-D, GO-300, IO-360-G, IO-360-K, TSIO-360, CRSIO-360-GB, O-470 B.M, O-470-L, O-470-R, O-470-U, O-470 Z.S, IO-470-C, IO-470-E, IO-470-F, IO-470-L, IO-470-N, IO-470-S, IO-470-V, IO-520-A, IO-520-B, IO-520-C, IO-520-D, IO-520-F, IO-520-K, IO-520-M, IO-520-W, TSIO-520, TSIO-520-C, TSIO-520-M, TSIO-520-N, TSIO-520-UB, GTSIO-520, IO-550-C, and R-670 reciprocating engines, installed on the following U.S. registered aircraft: N101G, N101JB, N101PQ, N1077B, N11PT, N111MK, N114R, N1162D, N1167J, N121LG, N124WN, N13159, N1344V, N1360L, N140NL, N1503S, N1556T, N1584V, N16165, N1672R, N1680R, N172CB, N1724T, N17793, N179SV, N1806F, N1818L, N182MC, N186Q, N19193, N19346, N207X, N200BD, N2051S, N2083S, N210KC, N21179, N2168N, N22FG, N2248Z, N2281T, N231KQ, N24FG, N2616N, N26560, N27G, N27326, N2841W, N2854W, N2881M, N2928B, N2995F, N3DX, N30C, N30CA, N300RS, N31CU, N313TM, N3145Y, N3153B, N323K, N3397Q, N340VV, N3499G, N35MX, N35840, N35964, N3599L, N3603L, N36319, N3700J, N39545, N4008F, N4088V, N41CU, N41032, N4105C, N4154Y, N421CW, N421EM, N421SM, N4218L, N4259B, N4302L, N4354K, N4354W, N444BJ, N4591S, N4598S, N4672B, N476KE, N4761K, N47964, N4812F, N4884J, N4895E, N5089V, N51EN, N5314T, N5357A, N5377J, N5453J, N550DF, N5517A, N555YT, N5591D, N57032, N5732X, N58BS, N5808F, N60DM, N60062, N6108F, N6158R, N6169N, N6193X, N62121, N6222F, N6278V, N6285H, N6341X, N6363K, N6421P, N65WW, N65031, N6527P, N6579M, N6664L, N6669X, N6670G, N66909, N6706G, N67249, N677PC, N6789R, N6800R, N6822R, N6837Q, N68937, N6915F, N6952M, N6992E, N704GY, N704NQ, N7125E, N714BD, N7208V, N721X, N724BE, N7248H, N7303Y, N7309Q, N732DD, N735DV, N739JG, N7405S, N758JF, N777E, N7981D, N800WB, N8103Z, N8107D, N81070, N8150Q, N8168U, N8170D, N8209M, N8241N, N8307D, N8308Z, N836BQ, N8426S, N8432Z, N8465L, N8491S, N85WB, N8501S, N8532R, N8579H, N8579M, N85797, N86VS, N8660M, N8669A, N8867T, N9099G, N9124U, N9157S, N91603, N91860, N922DK, N92465, N9410S, N9434N, N9435U, N9516Y, N9547U, N9597T, N9606Y, N96134, N9613Y, N9673L, N96761, N9764E, N9777R, N97799, N9833H, N984BC, and N9992G.

Compliance: Required as indicated, unless accomplished previously.

To prevent detonation due to low octane, which can result in severe engine damage and subsequent failure, accomplish the following:

  (a) For engines that are certified to operate on only 91 or higher octane aviation gasoline (avgas) within the next 2 hours time in service (TIS) after the effective date of this airworthiness directive (AD) perform an engine teardown and analytical inspection, and replace with serviceable parts as necessary in accordance with TCM Service Bulletin (SB) No. M88-10, dated August 24, 1988.

  (b) For engines that are certified to operate on 80 octane avgas, within the next 2 hours TIS after the effectivedate of this AD conduct a differential compression test on all cylinders in accordance with TCM SB No. M84-15, dated December 21, 1984, and examine the oil filter by cutting the oil filter apart and spreading the filter paper out to look for metal particles. If metal particles are present, or if one or more cylinders shows unacceptable compression as specified in TCM SB No. M84-15, dated December 21, 1984, perform an engine teardown and analytical inspection, and replace with serviceable parts as necessary in accordance with TCM SB No. M88-10, dated August 24, 1988.

  (c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine and Propeller Standards Staff. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Engine and Propeller Standards Staff.

NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine and Propeller Standards Staff.

  (d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

  (e) Priority Letter AD 94-14-12, issued June 23, 1994, becomes effective upon receipt.

## Rule preamble

### Supplementary information

94-14-12 Teledyne Continental

This priority letter airworthiness directive (AD) is prompted by reports of aviation gasoline (avgas) being contaminated by Jet A fuel. After investigation the source of the contamination has been determined to be the refiner of the avgas. Through its distribution system, the refiner inadvertently caused Jet A fuel to be loaded into distribution tanks intended for avgas. Contaminated avgas from these distribution tanks was then shipped to local fuel distributors. The Federal Aviation Administration (FAA) has determined that aircraft with certain Teledyne Continental Motors (TCM) engines installed were fueled with this contaminated mixture between May 22 and June 2, 1994, at Sacramento Executive (SAC) airport, or between May 18 and June 2, 1994, at Sacramento Metro (SMF) airport. The list of U.S. registered aircraft specified in the applicability paragraph of this AD is based on investigation of fueling records secured from the two affected airports, which the FAA has determined to represent the population of affected engines. This condition, if not corrected, could result in detonation due to low octane, which can result in severe engine damage and subsequent failure.

This AD requires engines certified to operate on 91 octane or higher avgas to undergo a teardown and analytical inspection for detonation damage, and engines certified to operate on 80 octane avgas to undergo inspection for evidence of possible internal engine damage. Engineering analysis of operating these engines with avgas contaminated with Jet A fuel indicates that actual damage to the engine may range from unnoticeable to very severe, according to the duration of run, engine power level, and level of contamination. Damage may be characterized by increased operating temperatures resulting in damaged intake valves and burned pistons, and excessive loads imposed by detonation. Since internal damage may not be assessed by any other method, engines certified to operate on 91 octane or higher avgas must undergo a teardown and analytical inspection and any parts showing signs of detonation damage must be replaced. Investigation revealed the lowest octane level of the contaminated fuel to be 83 octane, therefore engines certified to operate on 80 octane avgas need not undergo a teardown and analytical inspection unless evidence of internal engine damage is present by the required differential compression test and examination of the oil filter for metal particles. The refiner has advised the FAA that it will pay for any reasonable expense associated with the inspection and/or disassembly in accordance with the mechanic's and manufacturer's recommendations.

The FAA has reviewed and approved the technical contents of: TCM Service Bulletin (SB) No. M88-10, dated August 24, 1988, that specifies that reciprocating engines operated with lower octane than that approved for the engine or contaminated with Jet A fuel should undergo a teardown and analytical inspection as the engine could sustain damage that cannot be assessed by any other method; and TCM SB No. M84-15, dated December 21, 1984, that describes procedures for differential compression tests.

Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design that have been operated with contaminated fuel, this AD requires teardown and analytical inspection for engines certified to operate on 91 or higher octane avgas, and differential compression test and examination of the oil filter for engines certified to operate on 80 octane avgas. The actions are required to be accomplished in accordance with the SB's described previously.

Pursuant to the authority of the Federal Aviation Act of 1958, delegated to me by the Administrator, the following priority letter AD 94-14-12, applicable to the TCM reciprocating engines specified in this AD, is issued and is effective immediately upon receipt.

## Affected data sheets (15) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS E9CE](https://openairdocs.org/tcds/E9CE): Continental Aerospace Technologies, Inc.; names 24 of 28 models: TSIO-360-SB, TSIO-360-JB, TSIO-360-FB, TSIO-360-HB, TSIO-360-H, TSIO-360-NB, TSIO-360-GB, TSIO-360-E…
- [TCDS E7CE](https://openairdocs.org/tcds/E7CE): Continental Aerospace Technologies, Inc.; names 9 of 10 models: GTSIO-520-E, GTSIO-520-K, GTSIO-520-D, GTSIO-520-C, GTSIO-520-M, GTSIO-520-F, GTSIO-520-N, GTSIO-520-L…
- [TCDS E5CE](https://openairdocs.org/tcds/E5CE): Continental Aerospace Technologies, Inc.; names 7 of 18 models: IO-520-A, IO-520-B, IO-520-C, IO-520-F, IO-520-K, IO-520-M, IO-520-D
- [TCDS 3E1](https://openairdocs.org/tcds/3E1): Continental Aerospace Technologies, Inc.; names 6 of 19 models: IO-470-L, IO-470-S, IO-470-V, IO-470-N, IO-470-F, IO-470-E
- [TCDS E-298](https://openairdocs.org/tcds/E-298): Continental Aerospace Technologies, Inc.; names 6 of 6 models: GO-300-A, GO-300-F, GO-300-D, GO-300-E, GO-300-C, GO-300-B
- [TCDS E-273](https://openairdocs.org/tcds/E-273): Continental Aerospace Technologies, Inc.; names 4 of 21 models: O-470-R, IO-470-C, O-470-L, O-470-U
- [TCDS E8CE](https://openairdocs.org/tcds/E8CE): Continental Aerospace Technologies, Inc.; names 4 of 31 models: TSIO-520-M, TSIO-520-N, TSIO-520-C, TSIO-520-UB
- [TCDS E-252](https://openairdocs.org/tcds/E-252): Continental Aerospace Technologies, Inc.; names 3 of 15 models: O-200-A, O-200-C, O-200-B
- [TCDS E1CE](https://openairdocs.org/tcds/E1CE): Continental Aerospace Technologies, Inc.; names 2 of 18 models: IO-360-G, IO-360-K
- [TCDS ATC 80](https://openairdocs.org/tcds/ATC%2080): Continental Motors Inc; names 1 of 5 models: R-670
- [TCDS E-205](https://openairdocs.org/tcds/E-205): Continental Aerospace Technologies, Inc.; names 1 of 21 models: A-65-8
- [TCDS E-233](https://openairdocs.org/tcds/E-233): Continental Aerospace Technologies, Inc.; names 1 of 31 models: C85-12
- [TCDS E-246](https://openairdocs.org/tcds/E-246): Continental Aerospace Technologies, Inc.; names 1 of 11 models: E185-11
- [TCDS E-253](https://openairdocs.org/tcds/E-253): Continental Aerospace Technologies, Inc.; names 1 of 8 models: O-300-D
- [TCDS E3SO](https://openairdocs.org/tcds/E3SO): Continental Aerospace Technologies, Inc.; names 1 of 20 models: IO-550-C

## 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: 70,734 (0 by airframe model, 70,734 by engine model)
- Makers: Cessna 40,431, Beech 10,619, Piper 4,775, Aeronca 3,071, Taylorcraft 1,614, Cirrus Design 1,575, Luscombe 1,163, Mooney 1,136, Bellanca 586, Raytheon 545

Models with the most aircraft:

- [Continental O-470 series](https://openairdocs.org/engine/continental-o-470-series): 12,779 aircraft (engine model)
- [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series): 9,486 aircraft (engine model)
- [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series): 8,790 aircraft (engine model)
- [Continental A&C65 series](https://openairdocs.org/engine/continental-a-c65-series): 7,967 aircraft (engine model)
- [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series): 6,622 aircraft (engine model)
- [Continental C85 series](https://openairdocs.org/engine/continental-c85-series): 4,671 aircraft (engine model)
- [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series): 4,499 aircraft (engine model)
- [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series): 4,064 aircraft (engine model)
- [Continental IO-550 series](https://openairdocs.org/engine/continental-io-550-series): 3,077 aircraft (engine model)
- [Continental TSIO-360 series](https://openairdocs.org/engine/continental-tsio-360-series): 1,907 aircraft (engine model)
- [Continental IO-360 series](https://openairdocs.org/engine/continental-io-360-series): 1,885 aircraft (engine model)
- [Continental E185 series](https://openairdocs.org/engine/continental-e185-series): 1,108 aircraft (engine model)
- [Continental GO-300 series](https://openairdocs.org/engine/continental-go-300-series): 808 aircraft (engine model)
- [Continental GTSIO-520-C](https://openairdocs.org/engine/continental-gtsio-520-c): 387 aircraft (engine model)
- [Continental O-200 series](https://openairdocs.org/engine/continental-o-200-series): 329 aircraft (engine model)
- [Continental O-200A](https://openairdocs.org/engine/continental-o-200a): 295 aircraft (engine model)
- [Continental IO-470 series](https://openairdocs.org/engine/continental-io-470-series): 225 aircraft (engine model)
- [Continental IO-550-C](https://openairdocs.org/engine/continental-io-550-c): 199 aircraft (engine model)
- [Continental GTSIO-520 series](https://openairdocs.org/engine/continental-gtsio-520-series): 178 aircraft (engine model)
- [Continental R670-SERIES series](https://openairdocs.org/engine/continental-r670-series-series): 170 aircraft (engine model)

All 85 models: https://openairdocs.org/ad/94-14-12/models.md
Every aircraft: https://openairdocs.org/ad/94-14-12/aircraft.md

## Related documents

- [AD 95-21-15](https://openairdocs.org/ad/95-21-15): Aviation Gasoline · Continental Motors A-65-8, C85-12F, C85-12FJ and 77 more. Effective Nov 28, 1995. Supersedes this AD

Its text cites no advisory circulars or STCs.

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