Check Team FR Posted January 10, 2022 Share Posted January 10, 2022 APU GTCP85-180L run normally. Bleed air check > 35 psig For starting engine, pressure at pressure gage is superior to 30 psig. But with air conditionning cargo ans flight station comp on norm position, the pressure is under 22 psig. The EGT is adjust to 620°c RPM to 100%. Bleed air valve APU is checked. After that, the pressure is always under 22 psig. With only one air conditionning comp, how much is the pressure drop ? Thanks Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted January 14, 2022 Share Posted January 14, 2022 With cc pack on bleed air pressure should be around 35ps (32psi minimum), both packs should max out egt and pressure as low as 10psi, and unloaded should be above 38psi. Check air pressure regulator for 18.5 to 19.5psi Assuming load control valve and thermostat have been replaced, you are probably looking at erroded compressor, and therefore apu change Quote Link to comment Share on other sites More sharing options...
Check Team FR Posted January 19, 2022 Author Share Posted January 19, 2022 After adjustment of pneumatic thermostat at 620°C and RPM at 100%, we have a pressure at 21 psig max. (With 2 cc pack). The adjustment of air pressure regulator may be doing only with analyzer APU ? If the compressor was eroded, the pressure was under 22 psig for start engine like with 2 cc pack ? Do know if exist documentation on APU compressor liquid wash like engine (SP240) ? Thanks Quote Link to comment Share on other sites More sharing options...
Nate Anderson Posted February 23, 2022 Share Posted February 23, 2022 I've seen it before but there was a crack in the compressor. We had to borescope it to find it Quote Link to comment Share on other sites More sharing options...
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