ED Decision 2003/2/RM
1 General
1.1 In general the relight envelope required in CS 25.903(e)(2) may consist of two zones –
a. One zone where the engine is rotated by windmilling at or beyond the minimum rpm to effect a satisfactory relight, and
b. Another zone where the engine is rotated with assistance of the starter at or beyond the minimum rpm to effect a satisfactory relight.
1.2 The minimum acceptable relight envelope is defined in paragraph 2.
2 Envelope of Altitude and Airspeed
2.1 Sufficient flight tests should be made over the range of conditions detailed in 2.2 and 2.3, to establish the envelope of altitude and airspeed for reliable engine restarts, taking into account the results of restart tests completed by the engine constructor on the same type of engine in an altitude test facility or flying test bed, if available, and the experience accumulated in other aircraft with the same engine. The effect of engine deterioration in service should be taken into account.
2.2 Altitude and Configuration. From sea-level to the maximum declared restarting altitude in all appropriate configurations likely to affect restarting, including the emergency descent configuration.
2.3 Airspeed. From the minimum to the maximum declared airspeed at all altitudes up to the maximum declared engine restarting altitude. The airspeed range of the declared relight envelope should cover at least 30 kt.
2.4 Delay Tests. The tests referred to in paragraph 2.2 should include the effect on engine restarting performance of delay periods between engine shut-down and restarting of –
a. Up to two minutes, and
b. At least fifteen minutes or until the engine oil temperatures are stabilised at their cold soak value.
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