# AD 47-20-09: Voltage regulator check

- Type: Airworthiness directive
- Status: Current
- Products: Univair 415-C, 415-CD and 415-D
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 1,005 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F22E89C973198B2086256A4D005DEFE5.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-20-09

## The airworthiness directive

47-20-09 ERCO: (Was Service Note 1 of AD-718-6.) Applies to 415-C, -CD and -D Aircraft. Compliance required at each 100-hour inspection and immediately after each electrical system malfunction. Check the operation of the voltage regulator by observing the ammeter reading after starting and until the battery becomes charged. A normal operation would indicate a charging rate up to 11-13 amperes for periods of time up to 20 minutes after starting. The charging rate should reduce to 2 amperes or less within 2 hours or operation. (Ercoupe Service Department Memorandum No. 23 covers this same subject.)

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-718](https://openairdocs.org/tcds/A-718): Univair Aircraft Corporation; names 2 of 2 models: 415-CD, 415-C
- [TCDS A-787](https://openairdocs.org/tcds/A-787): Univair Aircraft Corporation; names 1 of 8 models: 415-D

## 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: 1,005 (1,005 by airframe model, 0 by engine model)
- Makers: Ercoupe 772, Engineering & Research 200, Forney 20, Erco 12, Univair 1

Models with the most aircraft:

- [Ercoupe 415-C](https://openairdocs.org/model/ercoupe-415-c): 623 aircraft (airframe model)
- [Engineering & Research 415-C](https://openairdocs.org/model/engineering-research-415-c): 160 aircraft (airframe model)
- [Ercoupe 415-D](https://openairdocs.org/model/ercoupe-415-d): 101 aircraft (airframe model)
- [Ercoupe 415-CD](https://openairdocs.org/model/ercoupe-415-cd): 48 aircraft (airframe model)
- [Engineering & Research 415-D](https://openairdocs.org/model/engineering-research-415-d): 24 aircraft (airframe model)
- [Forney 415-C](https://openairdocs.org/model/forney-415-c): 17 aircraft (airframe model)
- [Engineering & Research 415-CD](https://openairdocs.org/model/engineering-research-415-cd): 16 aircraft (airframe model)
- [Erco 415-C](https://openairdocs.org/model/erco-415-c): 7 aircraft (airframe model)
- [Erco 415-D](https://openairdocs.org/model/erco-415-d): 4 aircraft (airframe model)
- [Forney 415-D](https://openairdocs.org/model/forney-415-d): 2 aircraft (airframe model)
- [Forney 415-CD](https://openairdocs.org/model/forney-415-cd): 1 aircraft (airframe model)
- [Erco 415-CD](https://openairdocs.org/model/erco-415-cd): 1 aircraft (airframe model)
- [Univair 415-D](https://openairdocs.org/model/univair-415-d): 1 aircraft (airframe model)

All 13 models: https://openairdocs.org/ad/47-20-09/models.md
Every aircraft: https://openairdocs.org/ad/47-20-09/aircraft.md

Its text cites no advisory circulars or STCs.

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