Normal Law -> All systems go, you can rely upon the protections
Alternate Law -> There's something wrong - protections will try to help you but if you need full authority it's there.
Alternate Law 2 -> You're missing data required for the protections to work, but you've got full pitch and trim authority via your sidestick and thrust authority via the levers.
Direct Law -> Exactly what it says on the tin.
Question 1:
What are the differences between Alternate 1 and alternate 2 laws regarding
pitch? (Info below taken from an A330 Vacbi.)
Alternate 1:
The pitch attitude (Theta) protection is lost. High speed and stall protection are alternate.
Alternate 1A:
In addition the stall protection is lost.
Alternate 2:
The pitch attitude is lost and high speed and stall protection are alternate.
In addition the lateral normal law is lost and replaced by the lateral alternate law (roll direct and yaw alternate).
Alternate 2A:
In additition stall protection is lost.
Alternate 2B:
Pitch attitude, high speed, and stall protection are lost and the lateral normal law is replaced by lateral alternate law (bank angle protection lost).
With regards to "Pitch attitude is lost" in Alternate 2: Does this aggravate the situation perhaps in combination with a loss of- or unreliable pitch indication on the PFD (ADI portion) due to faulty/rejected ADIRU's? With the PF commanding a/c nose up, could he have been looking at an ADI telling him (erroneously) the a/c nose was pointing down?
Question 2:
Does the A330 FBW have a Flight Control System Self-test?
I remember way back in the 80's when I was a crewchief on the Viper. During launch, the pilot did pre-flight checks as I monitored launch procedures in concert with the pilot. One of them was the flight control self-test which was performed with assistance of the crewchief to monitor flight control surface deflections.
On one occasion the aircraft passed the flight control self-test as far as cockpit indications were concerned but I observed a jittering LH flaperon. I informed the pilot and he did a second self-test with the same results, the system passed the test but the jittering flaperon returned. After the sef-tests were completed, when the pilot moved the stick manually, the jittering was also observed as soon as the flaperon moved up or down from the neutral position. Obviously the flight was aborted and subsequent trouble shooting revealed a bad ISA (Integrated Servo Actuator). If I remember correctly a voting spool was the culprit.
Could the A330 FBW system have similar failures go undetected?