Reverse thrust in flight

[KLOS]

Would a Pro kindly explain the procedure for recovering from an uncommanded reverse thrust in the cruise.

Many thanks

[Rollingthunder]

Was on a DC8-63 coming back from Fiji (mostly snorkeling). Diving, caught a cold, kept diving. DC8 popped the inboards on arrival at YVR. Dropped like a stone. Nothing wrong with a/c but something was wrong with me. On the ground was totally deaf. Going through customs was interesting to say the least. When it hadn't cleared up a week later I went in for sinus surgery to fix the problem. Spent the next couple of weeks with cotton wool shoved up my nostrils.

[BOAC]

Would a Pro kindly explain the procedure for recovering from an uncommanded reverse thrust in the cruise.

- follow the QRH which normally ends with 'shut down the motor' if all else fails.

[Desert185]

dixi188:I was jumpseating on a UPS DC-8-73 some years ago when the capt. pulled the inboard reverse levers in descent. The Flight Engineer slapped his hand down and said "No you don't, not with these engines"

Maybe it was a UPS thing or just bad CRM.

UPS preferred that reversers not be used inflight unless for an emergency descent or for some other operational reason based on the Captain's judgment. It seems the FE may have acted inappropriately, even though he may have been right.

[Desert185]

klos:
Would a Pro kindly explain the procedure for recovering from an uncommanded reverse thrust in the cruise.

Many thanks

Depends on the aircraft.

DC-8: Reverse Thrust Lever - FORWARD IDLE; Emergency Stow Pump - ON; If reverser fails to stow: Engine - SHUTDOWN

Other aircraft without an emergency stow pump: Thrust Lever - IDLE; If the reverser doesn't stow - Engine - SHUTDOWN

Essentially, select idle power and hope it stows. If not, engine shutdown is necessary to reduce asymmetry. Most airplanes these days don't have buckets that reverse core air. Only the fan air is reversed, so the drag increase and asymmetry is less.

[KLOS]

Thanks BOAC and Desert 185 for your replies.

My ( lay) reading of the LAUDA B767 accident report was that the effect was to invert the aircraft resultng in its destruction by excessive G when recovery was attempted. As I recall the pilots were seeking to consult the manaual for guidance. Also as I mentioned originally , I understood that the sim reconsruction indicated a small window of circa 6 seconds for recovery . Have I got this right? - grateful for any further comment from the Pros.

Thanks

[BOAC]

The effect of a deployed reverser at high power (I think Lauda were climbing) is dramatic. A combination of loss of forward thrust, asymmetric couple and loss of lift from the disturbed airflow mean the rolling moment is huge, and 6 seconds may well be right. If action is not taken quickly extreme bank angles can develop.

It is also quite dramatic during take-off, especially with bucket type reversers since all engine-out performance calculations are negated. We have a thread somewhere about that.

[KLOS]

BOAC

Many thanks for this very informative response.