Originally Posted by
GarageYears
And
I'm a little bothered here. I truly believe most here are smart and understand systems analysis at least enough to comprehend what the Boeing AD is telling us here, but the statements above have me frowning. Is this really so confusing?
Boeing states that a failure of an AOA sensor can cause the AP to kick off or not be select-able in the first place if the AOA was already iffy. So let's assume that happened here. The crew took off things seemed fine, but once in the air they either engaged the AP which then dropped out, or were unable to engage the AP due to AOA disagreement. So no automatics. The AD is referring to stabilizer trim under control of the flight control computer, which with an iffy AOA input will cause nose down trim to be applied in increments lasting up to 10 seconds, while in manual flight.
They HAVE TO BE in manual because the very condition the AD refers to disables the autopilot.
So, no more "if only they turned on the AP", right?
- GY
You should not be bothered. Language in aviation in general, SBs and ADs in particular, is safety critical and should be clear, not contradictory and unambigious. This sentence MAY mean what you say, but it needs interpretation and twice thinking about it. This is bad and typical for lawyers. Boeing should know how to do better.