Bleed Air and Regulated Pressure

[Mark S]

On our 690B, The regulated pressure gauge reads fine in the green zone on the ground and ground idle.  Returns to green after a ground check of the de-ice boots too.

It does seem to drift to the high end of the red band in cruise flight.

I have not had a need to really count on the boots up to this point. Luckily no serious icing.
I did cycle the boots even though the dial was in the red and it looked like they inflated. Hard to quantify if they fully inflated or partially inflated.

I would assume any issues with the pressure would be the regulator and not bleed air.
Anyone had a similar issue?  I may have it looked at during the 150 hr coming up in a few months.

[donv]

I checked my 690 Flight Safety manual, and that indicates that it is probably the regulator. If the pressure is in the high red area, inflating the boots can damage them due to over-pressure.

This would be a good question for Barry Lane.

[Bruce Byerly]

Mark, if it’s in the red, it needs to be adjusted/fixed.

[Mark S]

To clarify,
My regulated pressure drifts down, from green to the low pressure band of red, but at the high end of that red band.
It is not over-pressured to the high red band. Not a good idea to test the boots in the high red area.
Regardless, I will be getting it fixed.

I have the flight safety study material, the official maintenance manual, and some other technical documents, but experience seems to be the best teacher.

[Mark S]

Late Update: the problem was indeed the regulator. Fixed several months ago.
My understanding is cabin pressure controllers don’t normally fail.
Any indication of cabin pressure problems combined with issues on the regulated air indicator or instrument air is likely the regulator.

I had the work done at Legacy Oklahoma.
.

[donv]

Glad you got it sorted!