Originally Posted by
malabo
Anybody hear anything from Leonardo on suggestions for QRH changes to ELECTRICAL FIRE/SMOKE?
My quick review of the crew's description from the NTSB preliminary report:
1. 7 minutes from landing they smelled plastic burning, no smoke, they turned the AC off.
2. A "few minutes later" they heard a "whoof" and the cabin filled with smoke, simultaneously low rpm warning and engine "overspeed" (overspeed N1, or just the PI to 145?), with collective lifting and cyclic displacing left.
3. Left seat pilot jettisons window to clear smoke, they try engine to idle but NR drops to the high 70's, they try diving but speed gets very high, so back to engine switch to idle/fly to get the RPM down.
Was hoping JGtn would tell us if the engines could have been switched to manual since at this point they are using the idle/fly switches to lower NR to descend, and it may have been smoother/easier manipulating both engines in manual and targeting a specific NR.
From the QRH: ELECTRICAL FIRE/SMOKE. If smoke or smell, try to identify cause and disconnect. If it cannot be identified then:
1. GEN 1, GEN 2 OFF
2. BATTERY MAIN OFF
3. OPEN WINDOWS TO VENTILATE COCKPIT
Note: AP2 and ATT will remain engaged but autopilot lights will be off.
Then it goes on.....
Not desk-flying the crew, they pulled a rabbit out of a hat, and I likely would be in a similar state of mind: VMC, 7 minutes out, smell plastic burning but no smoke, turn the AC off and let the greenies look at it on the ground. But from an OEM QRH perspective if on smelling plastic burning they had done step 1 wouldn't the #1 GEN have gone offline and stopped the 300amp current flow that was frying the collective tube? No "whoof" no need to jettison a window, no compromised integrity of the collective tube?
The engine systems are powered thanks to their own PMA (Permanent Magnetic Alternator) therefore remain in AUTO mode.
The engine mode switch FLIGHT or IDLE position being monitored by the EEC you can still control those two known status.
The GOVERNING modes either AUTO or MANUAL, selectable thanks to the GOV switches on the pilot collective should be operative, so they could revert to manual, but:
The ECL beep-trim, instead, need electrical power from the aircraft to operate the ECL, with the power OFF they are inoperative (the crew has reported it inoperative), it is then probably easier to control the engine power at two known power setting, rather than going all the way up to the overhead panel and try to adjust the power with no indication available.
Again that is an assumption.
Having said that, few indications lead us to believe than they effectively have lost the Essential busses such as the landing gear not being locked down, the engine beep trims inoperative, the engine not shutting down after having select the OFF mode on the engine mode switches ...
Not being a pilot myself, I can only say VERY GOOD JOB for having brought back the machine on the ground with no, or really little, personnel injuries!