Comment by stevenjgarner

Comment by stevenjgarner 3 hours ago

5 replies

The parallels with AA Flight 191 are striking. In THAT accident it was found [1]:

1) improper maintenance—American Airlines had used a forklift shortcut to remove the engine and pylon together, rather than following McDonnell Douglas’s prescribed method

2) The detachment tore away part of the wing’s leading edge, rupturing hydraulic lines and severing electrical power to key systems, including the slat-position indicator and stall warning (stick shaker).

3) The pilots followed the standard engine-out procedure and reduced airspeed to V₂, which caused the aircraft to stall and roll uncontrollably left. This procedure was later found out to be incorrect.

Defective maintenance practices, inadequate oversight, vulnerabilities in DC-10 design, and unsafe training procedures combined to cause the crash, killing all 273 people on board and leading to sweeping reforms in airline maintenance and certification standards.

[1] https://www.youtube.com/watch?v=F6iU7Mmf330

t0mas88 8 minutes ago

And just to add for those that aren't pilots: When they say "reduced airspeed to V2" that doesn't mean reducing engine power, it means pointing the nose higher while thrust remains at the maximum permissable setting. You're loosing speed but climbing faster.

This can happen if you accelerated past V2 (V2+20 is normal) before the engine failure and then after the failure you slow down to V2 to get the best climb angle on a single engine plus some safety margins above stall etc.

conradev 44 minutes ago

worth noting about AA191:

  With a total of 273 fatalities, the disaster is the deadliest aviation accident to have occurred in the United States.
akerl_ an hour ago

(asked earnestly out of lack of familiarity with this field) Are maintenance/certification standards distinct between passenger and cargo carriers?

It's hard for me to tell if this suggests a step backwards in application of the reforms instigated after AA191 or that those reforms were never copied over to cargo aviation.

  • noer an hour ago

    Yes but mostly related to purpose specific things: passenger carriers have additional safety checks for cabin things like seats, oxygen and evacuation systems. Cargo carriers have additional safety checks for things like cargo restraint and decompression systems.

    Furthermore (and I don't know if this is related to the cause of this crash), cargo jets tend to be older/refurbished passenger planes that have outlived their useful lives flying passengers.

daemonologist 40 minutes ago

To expand on #2, the loss of hydraulic pressure also caused the uncommanded retraction of the leading edge slats on the left wing, which was found by the NTSB to be part of the probable cause. Full report is here (PDF): https://www.ntsb.gov/investigations/AccidentReports/Reports/...

(I do not mean to imply that this exact slat retraction is necessarily relevant in the Louisville crash, however - I believe aircraft since AA191 are designed to maintain their wing configuration after loss of hydraulic pressure.)