| Tail Number / N-Number | N121C |
| Manufacturer | CRAIG VALENTINE |
| Model | SLING 4 TSI |
| Year Built | 2020 |
| Manufacturer's Serial Number | 170SK |
| 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 | ROTAX |
| Engine Model | 915 ISC3 A |
| Engine Type | 4 Cycle |
| Number of Engines | 1 engine |
| Horsepower | 141 hp (105 kW) |
| Kit Manufacturer | AIRPLANE FACTORY |
| Kit Model | SLING 4 TSI |
| Type of Registrant | Individual |
| Owner Name | VALENTINE CRAIG |
| Street | 2941 LINCOLN AVE |
| City | ALAMEDA |
| State | CA |
| Zip Code | 94501-3009 |
| Region | Western-Pacific |
| County | Alameda County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Experimental |
| Airworthiness Date | 2020-08-13 |
| Certificate Issue Date | 2020-07-31 |
| Last Action Date | 2020-07-31 |
| Expiration Date | 2027-07-31 |
| Status | Valid Registration |
| Mode S Code | 50053633 |
| Mode S Code Hex | A0579B |
Deregistered Aircraft 1 of 3. This aircraft was previously assigned the N-number N121C.
| Tail Number / N-Number | N121C |
| Manufacturer | AVIAT AIRCRAFT INC |
| Model | S-2C |
| Year Built | 1998 |
| Manufacturer's Serial Number | 6009 |
| 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 | LYCOMING |
| Engine Model | AEIO-540 SER |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 260 hp (194 kW) |
| Type of Registrant | Individual |
| Owner Name | BENHAM JERRY |
| Street | 1953 HAMBLETON DR |
| City | LORENA |
| State | TX |
| Zip Code | 76655-9744 |
| County | Alameda County |
| Country | US |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1998-10-31 |
| Certificate Issue Date | 2003-07-23 |
| Last Action Date | 2011-10-08 |
| Last Status | Valid Registration |
| Cancellation Date | 2012-10-19 |
| Exported To | AUSTRALIA |
Deregistered Aircraft 2 of 3. This aircraft was previously assigned the N-number N121C.
| Tail Number / N-Number | N121C |
| Manufacturer | CESSNA |
| Model | 550 |
| Manufacturer's Serial Number | 5500354 |
| Aircraft Type | Fixed wing multi engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 8 seats |
| Weight Class | CLASS 2 (12,500 - 19,999 pounds gross take off weight) |
| Number of Engines | 2 engines |
| Type of Registrant | Corporation |
| Owner Name | DIGITAL EQUIPMENT CORPORATION |
| Street | 1730 EAST RAMP LG HANSCOM FIELD |
| City | BEDFORD |
| State | MA |
| Zip Code | 01730 |
| County | Alameda County |
| Country | US |
| Certificate Issue Date | 1987-08-19 |
| Last Action Date | 1994-12-21 |
| Last Status | Valid Registration |
| Cancellation Date | 1995-03-03 |
| Exported To | CAYMAN ISLANDS |
Deregistered Aircraft 3 of 3. This aircraft was previously assigned the N-number N121C.
| Tail Number / N-Number | N121C |
| Manufacturer | MOONEY |
| Model | M-18C |
| Manufacturer's Serial Number | 202 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 1 seat |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Number of Engines | 1 engine |
| Average Cruising Speed | 103 miles per hour |
| Type of Registrant | Individual |
| Owner Name | ROOT WILBUR A |
| Street | HQ & GD CO 6103 ASUBR USDB |
| City | LOMPOC |
| State | CA |
| Zip Code | 93437 |
| Region | Western-Pacific |
| County | Alameda County |
| Certificate Issue Date | 1952-12-15 |
| Last Status | Valid Registration |
| Cancellation Date | 1953-11-12 |