# AD 78-23-10: Center Body Bellows Seal Assembly

- Type: Airworthiness directive
- Status: Current
- Products: Lycoming Engines AEIO-320-D1B, AEIO-320-E1A, AEIO-320-E1B, AEIO-320-E2A, AEIO-320-E2B, AEIO-360-A1A, AEIO-360-A1B, AEIO-360-A1B6, AEIO-360-A1C, AEIO-360-A1D, AEIO-360-A2A, AEIO-360-A2B and 209 more
- Effective: November 7, 1978
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Amendment: 39-3333
- Registered aircraft: 23,994 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7D7893E5D9226D948625684D007187AE.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/78-23-10

## The airworthiness directive

78-23-10 AVCO LYCOMING: Amendment 39-3333. Applies to all fuel injected Lycoming series engines equipped with the following Bendix Fuel Injector Models and Parts List Numbers.

Model Number Parts List Number RSA-5AB1 2524254-5 2524712-2 RSA-5AD1 2524054-5 2524147-7 2524213-5 2524291-5 2524359-4 2524450-3 2524550-2 2524673-2 2524682-2 2524742-2 2524752-1 RSA-7AA1 2524347-4 RSA-10AD1 2524163-8 2524163-7A 2524757-1 RSA-10DB1 2524275-9 2524649-3 RSA-10DB2 2524708-1 RSA-10ED1 2524273-5A 2524273-6 2524298-6 2524491-3 2524500-2A 2524500-3 2524693-2 2524709-1

Compliance required within the next 10 hours in service after the effective date of this AD, unless previously accomplished.

To prevent an in-flight power loss due to an over rich condition caused by the failure of the center body bellows seal assembly, replace the center body bellows seal assembly and tube bushing in accordance with Accomplishment and Identification instructions in the applicable Bendix Energy Controls Division Service Bulletin No. RS-52 Rev. 2 revised May 12, 1978, No. RS-53 Rev. 2 revised May 12, 1978, and No. RS-54 Rev. 2 revised May 10, 1978, or FAA approved equivalent.

Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration (FAA), Eastern Region.

As permitted by FARs 21.197 to 21.199, aircraft may be flown to a base where the modification required by this Airworthiness Directive can be accomplished.

NOTE: AVCO Lycoming Service Bulletins No. 428, No. 429 and No. 430 also pertain to this subject.

This amendment is effective November 7, 1978.

## Affected data sheets (15) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1E10](https://openairdocs.org/tcds/1E10): Lycoming Engines; names 65 of 89 models: IO-360-C1D6, AEIO-360-B1G6, HIO-360-B1B, IO-360-B2F6, HIO-360-C1B, AEIO-360-A1B6, AIO-360-A1B, IO-360-B2E…
- [TCDS 1E4](https://openairdocs.org/tcds/1E4): Lycoming Engines; names 55 of 81 models: IO-540-L1A5D, IO-540-M2A5D, IO-540-A1A5, IO-540-W1A5, IO-540-B1C5, IO-540-K1J5D, IO-540-G1A5, AEIO-540-D4B5…
- [TCDS 1E12](https://openairdocs.org/tcds/1E12): Lycoming Engines; names 28 of 32 models: AEIO-320-E1B, AIO-320-C1B, AIO-320-A1A, IO-320-B1C, IO-320-F1A, LIO-320-B1A, IO-320-B1D, AIO-320-A2B…
- [TCDS E14EA](https://openairdocs.org/tcds/E14EA): Lycoming Engines; names 21 of 40 models: TIO-540-G1A, LTIO-540-N2BD, TIO-540-A1A, TIO-540-A2A, TIO-540-C1A, LTIO-540-F2BD, TIO-540-J2BD, TIO-540-A2C…
- [TCDS 1E15](https://openairdocs.org/tcds/1E15): Textron Lycoming Subsidiary of Textron Inc.; names 11 of 12 models: IO-720-B1A, IO-720-D1CD, IO-720-A1A, IO-720-B1B, IO-720-D1BD, IO-720-C1BD, IO-720-A1BD, IO-720-A1B…
- [TCDS 1E7](https://openairdocs.org/tcds/1E7): Lycoming Engines; names 8 of 8 models: IGSO-540-A1F, IGSO-540-B1A, IGSO-540-A1H, IGSO-540-A1C, IGSO-540-A1A, IGSO-540-B1C, IGSO-540-A1D, IGSO-540-A1E
- [TCDS E-284](https://openairdocs.org/tcds/E-284): Lycoming Engines; names 7 of 23 models: IGSO-480-A1A6 (O-480-3), IGSO-480-A1B6, IGSO-480-A1C6, IGSO-480-A1F6, IGSO-480-A1E6, IGSO-480-A1G6, IGSO-480-A1D6
- [TCDS 1E11](https://openairdocs.org/tcds/1E11): Lycoming Engines; names 6 of 6 models: IGO-540-B1B, IGO-540-B1A, IGO-540-B1C, IGO-540-A1A, IGO-540-A1C, IGO-540-A1B
- [TCDS E19EA](https://openairdocs.org/tcds/E19EA): Lycoming Engines; names 6 of 6 models: TIGO-541-C1A, TIGO-541-G1AD, TIGO-541-D1B, TIGO-541-E1A, TIGO-541-B1A, TIGO-541-D1A
- [TCDS E10EA](https://openairdocs.org/tcds/E10EA): Lycoming Engines; names 5 of 5 models: TIO-541-E1A4, TIO-541-E1B4, TIO-541-E1C4, TIO-541-A1A, TIO-541-E1D4
- [TCDS E16EA](https://openairdocs.org/tcds/E16EA): Lycoming Engines; names 4 of 4 models: TIO-360-A1B, TIO-360-A1A, TIO-360-C1A6D, TIO-360-A3B6
- [TCDS E-275](https://openairdocs.org/tcds/E-275): Lycoming Engines; names 2 of 33 models: IGO-480-A1B6, IGO-480-A1A6
- [TCDS 1E1](https://openairdocs.org/tcds/1E1): Lycoming Engines; names 1 of 4 models: IVO-360-A1A
- [TCDS 1E14](https://openairdocs.org/tcds/1E14): Lycoming Engines; names 1 of 2 models: TIVO-540-A2A
- [TCDS E11EA](https://openairdocs.org/tcds/E11EA): Lycoming Engines; names 1 of 1 models: IVO-540-A1A

## 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: 23,994 (0 by airframe model, 23,994 by engine model)
- Makers: Piper 9,587, Cessna 3,347, Mooney 2,226, Beech 773, Bellanca 689, Aviat 334, Rockwell International 315, Robinson Helicopter 303, Maule 293, American Champion 281

Models with the most aircraft:

- [Lycoming I0360 series](https://openairdocs.org/engine/lycoming-i0360-series): 6,174 aircraft (engine model)
- [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series): 4,886 aircraft (engine model)
- [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series): 4,219 aircraft (engine model)
- [Lycoming IO-320 series](https://openairdocs.org/engine/lycoming-io-320-series): 1,707 aircraft (engine model)
- [Lycoming IO-360-B4A](https://openairdocs.org/engine/lycoming-io-360-b4a): 985 aircraft (engine model)
- [Lycoming AEIO-360 series](https://openairdocs.org/engine/lycoming-aeio-360-series): 882 aircraft (engine model)
- [Lycoming IO-360-A1B6D](https://openairdocs.org/engine/lycoming-io-360-a1b6d): 844 aircraft (engine model)
- [Lycoming AEIO-540 series](https://openairdocs.org/engine/lycoming-aeio-540-series): 433 aircraft (engine model)
- [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series): 336 aircraft (engine model)
- [Lycoming TI0-541 series](https://openairdocs.org/engine/lycoming-ti0-541-series): 271 aircraft (engine model)
- [Lycoming IO-540-D4A5](https://openairdocs.org/engine/lycoming-io-540-d4a5): 237 aircraft (engine model)
- [Lycoming IO-360 series](https://openairdocs.org/engine/lycoming-io-360-series): 217 aircraft (engine model)
- [Lycoming IO-360-A1A](https://openairdocs.org/engine/lycoming-io-360-a1a): 196 aircraft (engine model)
- [Lycoming IO-360-A1D6](https://openairdocs.org/engine/lycoming-io-360-a1d6): 192 aircraft (engine model)
- [Lycoming TIO-540 series](https://openairdocs.org/engine/lycoming-tio-540-series): 190 aircraft (engine model)
- [Lycoming IO-540-C4B5](https://openairdocs.org/engine/lycoming-io-540-c4b5): 179 aircraft (engine model)
- [Lycoming I0-360-B1E](https://openairdocs.org/engine/lycoming-i0-360-b1e): 141 aircraft (engine model)
- [Lycoming IO-360-A1B6](https://openairdocs.org/engine/lycoming-io-360-a1b6): 141 aircraft (engine model)
- [Lycoming IO-720 series](https://openairdocs.org/engine/lycoming-io-720-series): 120 aircraft (engine model)
- [Lycoming IO-360-A3B6D](https://openairdocs.org/engine/lycoming-io-360-a3b6d): 74 aircraft (engine model)

All 146 models: https://openairdocs.org/ad/78-23-10/models.md
Every aircraft: https://openairdocs.org/ad/78-23-10/aircraft.md

Its text cites no advisory circulars or STCs.

## NTSB investigations that cite this AD (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB MIA00LA053](https://openairdocs.org/ntsb/MIA00LA053), Dec 18, 1999: Swertfeger Velocity 173 Elite (N627KB), Murfreesboro, TN, substantial damage, 1 fatal. Probable cause: The failure of an unknown maintenance person to comply with an Airworthiness Directive (replace center body bellows seal assembly and tube bushings) and Service Bulletin (replace fuel diaphragm)…

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