| Tail Number / N-Number | N4221U |
| Manufacturer | CESSNA |
| Model | 150D |
| Year Built | 1964 |
| Manufacturer's Serial Number | 15060221 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 2 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | SUBARU |
| Engine Model | ALL MDLS A/B |
| Engine Type | 4 Cycle |
| Number of Engines | 1 engine |
| Horsepower | 400 hp (298 kW) |
| Average Cruising Speed | 90 miles per hour |
| Type of Registrant | Individual |
| Owner Name | MCWILLIAMS ROBERT P |
| Street | 245 WILDHORSE TRL |
| City | BELGRADE |
| State | MT |
| Zip Code | 59714-9506 |
| Region | Northwest Mountain |
| County | Gallatin County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Experimental |
| Airworthiness Date | 2003-07-07 |
| Certificate Issue Date | 2001-11-05 |
| Last Action Date | 2021-10-10 |
| Expiration Date | 2029-01-31 |
| Status | Valid Registration |
| Mode S Code | 51202633 |
| Mode S Code Hex | A5059B |