What are the two types of fuel cells used in aircraft?

The correct answer identifies the two primary types of fuel cells utilized in aircraft: integral or wet wing fuel cells and bladder-type fuel cells.

Integral fuel cells, also referred to as wet wing fuel cells, are built into the structure of the wing, using the wing's space to store fuel. This design maximizes the use of available space and reduces the overall weight of the aircraft since the fuel cell becomes part of the airframe itself. The fuel in these cells is contained in sealed compartments that are designed to minimize the risk of leaks and structural failure.

Bladder-type fuel cells, on the other hand, are flexible bags made from specialized materials that can expand and contract as they fill and empty with fuel. These bladders can be placed in a variety of spaces within an aircraft and can be more easily replaced or repaired than integral fuel cells. They are particularly useful in smaller aircraft or those with less complex fuel systems.

Understanding the different types of fuel cells is crucial in aviation, as it relates directly to fuel management, weight considerations, and maintenance procedures, influencing performance and safety in flight operations.