Configuration Deviation List (CDL

Similar to the MEL, a CDL (FAA-approved Configuration Deviation List) contains additional items and limitations for operation without secondary airframe or engine parts, while still allowing the aircraft to be considered airworthy. Items such as missing inspection panels, access doors, or aerodynamic fairings are found in the CDL. The CDL is kept with the MEL, uses the same notebook format, and must always be onboard the aircraft. CDLs, like MELs, are important because they allow flights to be conducted that are still considered “safe” by the FAA even though certain equipment is inoperative, damaged, or missing.

The CDL must be referenced prior to flight for any performance penalties, limitations, or procedures to be applied for operation without some particular item. For example, a missing aerodynamic fairing may impose such a drag penalty that the aircraft must be dispatched with a greater than normal fuel load, thereby potentially displacing passengers or baggage.