Individually Owned: 150,657
Corporate Owned: 137,281
Hirth Hm 504 Aircraft Engine
| Manufacturer Name | Hirth |
| Model Name | Hm 504 |
| Aircraft Engine Type | Reciprocating |
| Horsepower or Pounds of Thrust (For Reciprocating Engines) |
100 hp |
| Thrust | n/a |
| Number of aircraft regsitrations with this engine type | 4 |