787 ground test enable switch

[RMC]

Had a pilot today (unaware of whether engineers were working on the aircraft) move it from enable back to normal.

There were engineers working on it but his response afterwards was that there would have been no problem anyway as the flying controls would have been locked out to prevent any unwanted control surface movement.

What tests is that switch used for, is he right that there is no chance of someone potentially getting hurt?

[HOVIS]

Silly pilot.
Not much chance of someone getting hurt but a good chance the trouble shooting results from the test will be compromised.
That switch is selected prior to almost all BITE System tests. It allows systems to operate during tests that would normally be inhibited. EG CAC/Pack with only two Ground Electrical Power sources.
If the engineers are working on the aircraft please ask before touching anything. We're just trying to do our job as quickly as possible, the aircraft will be ready when it's ready, not before.

[RMC]

Thanks Hovis, I only ask as I want to emphasise to this guy that moving the switch is a big no no,One of our engineers said that if there were any tests that were likely to cause an unpleasant surprise then there would be an engineer in the cockpit and pilots wouldn’t be allowed in. Is there any test which the enable postition would be used that falls into this category. Or there are no tests that would move say thrust reverser trim, spoiler or primary Control surface.

[spannersatcx]

An interactive tests that involves T/R or flying control movement then there should be someone in the flt deck, also some tests can be quite lengthy but don't require any interaction, 60 minutes or more, so could potentially compromise this, having to start again, with a possible delay. I always try to be there, to advise crew please don't touch.... That said it would be courteous to check before moving grnd test enable etc, as we can not always be in 2 places at once. A lot of tests on the 350 for instance require ADIRU alignment, first thing crew do on arrival, start a realignment, so if I know the crew are imminent I will endeavour to tell them, and to be fair a lot of our crews do ask first.

[RMC]

Thanks SS so are there tests which involve T/R or flying control movement which would require the switch to be moved to the ground test position. I know what you are saying about someone should always be in the flight deck, but am concerned commercial pressures mean we may not always have as many engineers available as we would like.

[HOVIS]

There are definitely flt control tests that would need the ground test switch enabled. But as has been said, if hydraulics are supplied then I would expect a big 'DO NOT TOUCH ANYTHING' Placard on the pedestal at the very least.