47-20-09: Voltage regulator check
FAA order 47-20-09 is an airworthiness directive. The FAA's subject line: Voltage regulator check. System: electrical power.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Univair Aircraft Corporation
- Models
- 415-C, 415-CD, 415-D
Dates and paperwork
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (610 characters)
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.)
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/47-20-09.json · aircraft systems.