| Tail Number / N-Number | N4021S |
| Type of Reservation | Reserved to manufacturer - temporary number |
| Reserving Party Name | BOEING CO |
| Street | 737 LOGAN AVE N |
| City | RENTON |
| State | WA |
| Zip Code | 98057 |
| Date Reserved | 2019-08-02 |
Deregistered Aircraft 1 of 2. This aircraft was previously assigned the N-number N4021S.
| Tail Number / N-Number | N4021S |
| Manufacturer | AYRES CORPORATION |
| Model | S2R-600 |
| Year Built | 1980 |
| Manufacturer's Serial Number | 2561R |
| 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) |
| Engine Manufacturer | P&W |
| Engine Model | R1340 SERIES |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 600 hp (448 kW) |
| Type of Registrant | Corporation |
| Owner Name | AIRCRAFT ESCROW & TITLE CO |
| Street | 108 W 13TH ST |
| City | WILMINGTON |
| State | DE |
| Zip Code | 19801-1145 |
| Country | US |
| Airworthiness Classification | Restricted |
| Airworthiness Date | 1980-07-01 |
| Certificate Issue Date | 2013-10-18 |
| Last Action Date | 2013-10-18 |
| Last Status | Valid Registration |
| Cancellation Date | 2013-11-08 |
| Exported To | GUATEMALA |
Deregistered Aircraft 2 of 2. This aircraft was previously assigned the N-number N4021S.
| Tail Number / N-Number | N4021S |
| Manufacturer | SIKORSKY |
| Model | S-61D |
| Manufacturer's Serial Number | 61497 |
| Aircraft Type | Rotorcraft |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 28 seats |
| Weight Class | CLASS 2 (12,500 - 19,999 pounds gross take off weight) |
| Number of Engines | 2 engines |
| Average Cruising Speed | 129 miles per hour |
| Type of Registrant | Corporation |
| Owner Name | SIKORSKY AIRCRAFT DIVISION UNITED AIRCRAFT CORP |
| Street | MAIN ST |
| City | STRATFORD |
| State | CT |
| Zip Code | 06602 |
| Region | New England |
| Certificate Issue Date | 1972-05-01 |
| Last Status | Valid Registration |
| Cancellation Date | 1972-05-23 |
| Exported To | ARGENTINA |