AMC E 890 Thrust Reverser Tests

ED Decision 2018/014/R

(1)     Interpretation of CS-E 890(g):

In cases where the Engine test of CS-E 740 cannot be run with the standard thrust reverser, for example because it is not available despite the applicant’s efforts to obtain it, it is acceptable that a suitably representative test  reverser is fitted for the endurance test.

This addresses only the passive effects of the thrust reverser: cantilevered weight, the effect on vibrations and the loading of the Engine carcass, etc. Other evidence will be necessary to address the effects of the thrust reverser when functioning.

It is also acceptable to use other Engine tests performed with a representative thrust reverser, such as cyclic tests performed for the ETOPS approval of the aircraft.

(2)     Representative control system.

It is not necessary that the whole control system (i.e. up to throttle levers) be representative of that of standard production thrust reverser. The necessary components of the control system are those situated on the powerplant assembly (nacelle) and which are subject to functioning when the reverser deployment is requested. This includes magnetic, hydraulic, electric, actuated controls but not necessarily the supply upstream, depending on the installation. The automatic throttle retarder system and forward thrust restrictor should be representative of the standard reverser system, but the control from pylon to flight deck need not be. Provision for instrumentation in the nacelle area are necessary for test follow up.

(3)     Duration of use.

Thrust reverser intended for ground use only addressed in CS-E 890(c), as opposed to in-flight use addressed in CS-E 890(d), means a thrust reverser for which there is a means to prevent the reverser from deploying in flight.

The cycles prescribed in CS-E 890(c)(1) refer to a duration of use for which approval is sought. When no particular use is intended other than the braking during post-landing and taxiing, it is commonly assumed that the duration should be taken as 30 seconds.

For in-flight use, in CS-E 890(d), when no particular value is foreseen for duration use, the duration should be taken equal to one minute.

During the tests prescribed under CS-E 890(c) and (d), the cycles to be run up to the «declared maximum reverse thrust conditions» should be such as to explore the Engine/reverser combination up to conditions likely to be encountered inside the declared envelope for use of the thrust reverser, in terms of temperatures (EGT) and pressures.

The required reverser operation cycles conducted should average no less than 100 percent of the specified maximum thrust conditions for maximum forward and maximum reverse. While some reverser operating cycles are acceptable with operation below the specified thrust values, to be credited the gas temperature should be maintained at least to the specified 100 percent value.

(4)     Combination of tests.

The tests of CS-E 890 may be combined with parts of the Endurance Test of CS-E 740 by suitable arrangement in agreement with the Agency. For example, test of CS-E 890(c)(1) may be combined with idling periods of Part 1 and 5 of the Endurance Test provided the idling period with forward thrust is not reduced to less than 3 ½ minutes per cycles.

[Amdt No: E/1]

[Amdt No: E/5]