| Tail Number / N-Number | N4123D |
| Manufacturer | HELIO |
| Model | H-391B |
| Year Built | 1957 |
| Manufacturer's Serial Number | 042 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 4 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | LYCOMING |
| Engine Model | GO-435C&D SER |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 260 hp (194 kW) |
| Average Cruising Speed | 117 miles per hour |
| Type of Registrant | Individual |
| Owner Name | THUN KARL J |
| Street | PO BOX 10 |
| City | GRAHAM |
| State | WA |
| Zip Code | 98338 |
| Region | Northwest Mountain |
| County | Pierce County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1957-03-26 |
| Certificate Issue Date | 1978-03-03 |
| Last Action Date | 2022-11-04 |
| Expiration Date | 2030-02-28 |
| Status | Valid Registration |
| Mode S Code | 51157123 |
| Mode S Code Hex | A4DE53 |