| AD Number | 53-03-01 | Status | Active |
| Effective Date | Not specified | Issue Date | Not specified |
| Docket Number | Unknown | Amendment | N/A |
| Product Type | ["Aircraft"] | Product Subtype | ["Small Airplane"] |
| CFR Part | --- - Part 39 | CFR Section | N/A |
| Citation | This information is not available. | ||
| Manufacturer(s) | Sierra Hotel Aero, Inc. |
| Model(s) | Navion B |
53-03-01 NAVION: Applies to All Model B Aircraft Equipped With Hartzell HC-12 X20-8C/9333C-0 Propellers.
Compliance required not later than March 15, 1953.
Vibration tests conducted subsequent to the initial tests of the Hartzell HC-12 X20- 8C/9333C-0 propeller installed on the Lycoming GO-435 engine revealed vibration characteristics of a hazardous nature. Therefore, to prevent possible blade cracks and/or failures, the existing r.p.m. restriction placard should be revised as follows:
"Avoid continuous ground operation between 1675 and 2150 engine r.p.m."