wet

In aviation maintenance, a "wet" engine is one operating with afterburners lit or water injection active, both methods that temporarily boost thrust output beyond the engine's dry (unaugmented) rating. This distinction matters because wet and dry operation place fundamentally different loads on the engine, demand different maintenance intervals, and require different technical checks before flight.

Afterburners, found on military jets and some high-performance aircraft, inject fuel directly into the exhaust stream behind the turbine, igniting it for a sharp thrust increase. Water injection, used historically and still on some turboprops and older turbojets, sprays demineralized water into the compressor inlet to cool incoming air, allowing denser air charge and higher thrust without exceeding turbine temperatures. Both methods reduce engine life per operating hour and are used only when needed: carrier launches, combat maneuvering, or rapid climb.

A crew will request "wet" operation only during specific mission phases. The maintenance team must verify fuel system integrity, ignition systems, and water system cleanliness before these augmentation modes are approved. Flight engineers monitor engine temperatures and pressures continuously during wet operation because the engine is working at limits it was not certified to sustain indefinitely.

The term reflects the physical reality: water injection literally adds moisture to the engine, while afterburners create a wet, sooty exhaust plume visible from the ground. In contrast, dry thrust is what the core engine produces on its own, without any injection or augmentation. Modern turbofans rarely use either method; instead, higher bypass ratios provide the thrust increase that older designs needed augmentation to achieve.