52-04-07: Heater Control Modification
FAA order 52-04-07 is an airworthiness directive. The FAA's subject line: Heater Control Modification. System: heating, ice protection and utility systems.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Martin-Marietta Corporation
- Models
- 202, 202A
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 (934 characters)
52-04-07 MARTIN: Applies to All Models 202 and 202A Aircraft Except as Noted.
Compliance required not later than July 1, 1952.
The following controls and their wiring are common to two wing anti-icing heaters. The controls listed are identical in each nacelle. Modify the system so each of the controls serves only one heater:
1. Emergency high heat 400 degrees cutout switch.
2. Firewall shutoff switch.
3. Fuel pump circuit breaker (supplies power to ignition controls and master fuel controls).
4. Fuel shutoff relay.
5. Wiring to the master and auxiliary solenoid valves.
6. Fuel booster pump relay (has dual power input but single ground on the control circuit).
7. Ignition relay (202 only).
8. Ignition transformer (202 only).
9. Ignition circuit breaker (202 only).
10. AC safety relay (202 only).
(Trans World Airlines Engineering Order 5838 covers this same subject for the 202A).
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/52-04-07.json · aircraft systems.