14 CFR § 49.53

A conveyance is eligible for recording under this subpart only if, in addition to the requirements of §§ 49.11, 49.13, and 49.17, the following requirements are met:

It affects any aircraft engine, propeller, appliance, or spare part, maintained by or on behalf of an air carrier certificated under 49 U.S.C. 44705;

It contains or is accompanied by a statement by the air carrier certificated under that section;

It specifically describes the location or locations of each aircraft engine, propeller, appliance, or spare part covered by it; and

It is accompanied by the recording fee required by § 49.15, but there is no fee for recording a conveyance named in § 49.51(c).

The conveyance need only describe generally, by type, the engines, propellers, appliances, or spare parts covered by it.