47-21-15: Radio Filters
FAA order 47-21-15 is an airworthiness directive. The FAA's subject line: Radio Filters. System: instruments and avionics.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Sky Enterprises, Inc.
- Models
- RC-3
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 (1,024 characters)
47-21-15 REPUBLIC: (Was Mandatory Note 5 of AD-769-2.) Applies to Model RC-3 Aircraft Serial Numbers 488 to 602, Inclusive.
Compliance required as soon as possible, but not later than July 1, 1947.
Inspect the radio filter mounted on left-hand rear engine baffle. Filters in steel boxes 4 inches by 2 inches should be further inspected and reworked or replaced as described below, in order to minimize the possibility of a short circuit. Those filters which are in a smaller box need not be reworked.
1. If the coil is bolted to the box and the condenser is fastened in place with a clamp, the filter is satisfactory. If the coil is bolted to the box but the condenser is glued in place, the filter may be used provided a 1 1/8-inch diameter clamp is added to fasten the condenser in place.
2. Filters in which the coil is not bolted to the box should be replaced by a new filter assembly, Republic P/N SK-17-83053-1.
(Republic RC-3 Seabee Service Bulletin No. 15 dated April8, 1947, 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/47-21-15.json · aircraft systems.