| Tail Number / N-Number | N551X |
| Manufacturer | THOMAS N HELM |
| Model | SONEX ONEX |
| Year Built | 2021 |
| Manufacturer's Serial Number | ONX0137 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Not Type Certificated |
| Number of Seats | 1 seat |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | AEROCONVER |
| Engine Model | AEROVEE |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 80 hp (60 kW) |
| Kit Manufacturer | SONEX AIRCRAFT LLC |
| Kit Model | ONEX |
| Type of Registrant | Individual |
| Owner Name | HELM THOMAS N |
| Street | 1335 LORI DR |
| City | NEENAH |
| State | WI |
| Zip Code | 54956-1998 |
| Region | Great Lakes |
| County | Winnebago County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Experimental |
| Airworthiness Date | 2021-06-17 |
| Certificate Issue Date | 2020-05-12 |
| Last Action Date | 2023-01-22 |
| Expiration Date | 2027-05-31 |
| Status | Valid Registration |
| Mode S Code | 51602457 |
| Mode S Code Hex | A7052F |
Deregistered Aircraft 1 of 2. This aircraft was previously assigned the N-number N551X.
| Tail Number / N-Number | N551X |
| Manufacturer | ELDREDGE KEVIN |
| Model | S51 |
| Year Built | 2002 |
| Manufacturer's Serial Number | 076 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Not Type Certificated |
| Number of Seats | 2 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | AMA/EXPR |
| Engine Model | UNKNOWN ENG |
| Number of Engines | 1 engine |
| Type of Registrant | Individual |
| Owner Name | HAMBLETON JOHN A |
| Street | 9420 NW 125TH AVE |
| City | OCALA |
| State | FL |
| Zip Code | 34482-8648 |
| County | Winnebago County |
| Country | US |
| Airworthiness Classification | Experimental |
| Airworthiness Date | 2002-05-17 |
| Certificate Issue Date | 2003-09-04 |
| Last Action Date | 2009-08-18 |
| Last Status | First Notice for Re-Registration/Renewal |
| Cancellation Date | 2012-04-12 |
Deregistered Aircraft 2 of 2. This aircraft was previously assigned the N-number N551X.
| Tail Number / N-Number | N551X |
| Manufacturer | BOEING |
| Model | A75N1 |
| Manufacturer's Serial Number | 75267 |
| 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) |
| Number of Engines | 1 engine |
| Type of Registrant | Corporation |
| Owner Name | PARKER AVIATION ENTERPRISES INC |
| Street | BOX 311 |
| City | WARREN |
| State | VT |
| Zip Code | 05674 |
| Region | New England |
| County | Winnebago County |
| Certificate Issue Date | 1994-07-05 |
| Last Status | Valid Registration |
| Cancellation Date | 1995-07-10 |
| Exported To | PARAGUAY |