| Clue | Source | Date |
|---|---|---|
| Engine opening, inertia beaten with a kick-starter | ||
| Front part of a jet engine | New York Times | 10 Nov 2015 |
| Internal combustion engine system | LA Times Daily | 12 Sep 2015 |
| Internal combustion engine system | ||
| Front part of a jet engine | ||
| Jet engine opening | ||
| Opening of a fuel-burning engine | ||
| Internal combustion engine system |