Originally Posted by
oliver2002
Well, Lauda 4 operated by a 763 also had a thrust reverser deploy in 1991 and Boeing claimed it was possible to recover from it.
Only Niki Lauda offering to test such a situation himself bought about an admission.
https://en.m.wikipedia.org/wiki/Lauda_Air_Flight_004
Wiki is far from an authority. I was personally involved in the investigation, and early on it
was believed to be recoverable. Boeing did test an in-flight deployment during the original 767 certification flight testing - and it was controllable (at ~200 knots and the engine at idle). Early on, Niki did try it in the simulator and agreed it should have been controllable - however what was programed in the simulator didn't accurately represent 'real world' when a reverser deployed at Mach 0.78/23k/max climb power.
It took months of investigation and wind tunnel testing to understand why it wasn't controllable - after which Boeing added the third lock. I was part of the wind tunnel testing of what a hi-bypass wing mounted engine could do if it deployed in-flight with the engine at high power. I'll always remember the aero S&C guy during the testing - he was rather arrogant and before we'd started he was positive that it was controllable - even volunteered to go on a flight test to test the exact Lauda scenario. But after we started testing and he examined the data, he started getting real quiet, and by the time we finished up he wouldn't talk to most of us. Last test we did was a flow visualization using hundreds of yarn tufts. It was frightening to witness - with the engine at power, the reverser efflux basically blanked out most of the upper surface of the wing on that side. The wing would have dropped like a rock.
What's not commonly known is that when the FAA/JAA went to Airbus and wanted them to add a third lock, Airbus refused, claiming that it could never happen with their system. Until it did. They very nearly had their own Lauda - they were fortunate that the reverser re-stowed and the pilot was barely able to regain control and save it.