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I wonder if there was sufficient institutional memory to consider this during the 737MAX certification. In a 1992 recorded interview David P. Davies -- chief p
by Treblemaker 8y ago
I wonder if there was sufficient institutional memory to consider this during the 737MAX certification.
In a 1992 recorded interview David P. Davies -- chief pilot of the UK Air Registration Board (ARB) from the 1950's through 1970's -- described a problem during certification of a new 707 variant that is remarkably similar to the recent 737MAX issue.
Fascinating full set of interviews at the main site if you have time to listen to them:
https://soundcloud.com/aerosociety-podcast/sets https://soundcloud.com/aerosociety-podcast/sets
(scroll down to "An Interview With...", and scroll that list for "The D. P. Davies Interview", #'s 19, 18, 17, 16)
Summary: 707-330C variant added leading-edge devices to the wing that caused center of lift to move forward at high Angle of Attack, increasing the pitching moment and reducing the stick forces. Even though the stall behavior was fairly benign, Davies refused to certify it against broad opposition from the airline customers, Boeing, and even his own management in the ARB.
A significant part of his argument was (what I now know as) "Normalization of Deviance". They "solved" it by adding a stick pusher to "nudge" the yoke forward in certain conditions.
- nutcracker46 8y agoIt sure appears that the 707 flew like a truck. Not simply a truck, but a truck with too small a rudder. Davies certainly didn't like the low V speeds / difficult controllability in the original version. You know there's a problem when the manufacturer doesn't like being aboard for an engine out test around Vmcg. Goddam those pilots goofing off, rolling the 707. And then, the others doing excessive Dutch roll without yaw dampers on...