These recommendations are written to cover the subject of engine exhaust gas to air type heat exchangers under the following classifications:

Cabin Heating: (All occupied regions and windshields heating).

Wing and empennage heating

Engine and Accessory Heating: (When heater is installed as part of the aircraft).

These recommendations are not intended to cover the design of secondary exchangers which may be required when engine exhaust gas to air type heat exchangers are used in supplying ventilating air.

PURPOSE:

This recommended practice is to be considered as being currently applicable and necessarily subject to revision from time to time, due to rapid development of the aircraft industry.

The following recommendations are based on practical engineering requirements for the design and testing of such engine exhaust gas to air type heat exchangers as are now used on airplanes and for such as may be developed to meet later requirements.