Is there any scenario where this is ok on the Aerostar?
Pretty sure it happened while sitting there, sometime in the last 24 hrs or so.

Tail #?

Best guess:

Pilot ran flaps up and down to bleed off the pressure in the hydraulic accumulator and has crud in the flap tracks.

Peak in the right side and look for the hydraulic pressure gauge.

IF he left the flap selector in the up position the split will resolve when the right engine starts. (Flaps will come up).

It's unknown what will happen if he sets 20 deg for TO.

I didn't want to post it without talking to him first. He's pretty sure it's due to a small hydraulic leak, allowing that side to bleed down.
I assumed the flaps would have a physical linkage, guess not, interesting.
Looks like a nice plane.

Jack - you might consider deleting the other 4 threads on this topic. Some weirdness today it seems on BT causing multiples.

That's Frank Lenzi's plane - yes it is a great aircraft. Home in Waterloo Ontario - presently in FLA

Bob Keeping

Thanks Lee, done. Strange.

Great guy on the phone. He explained the Aerostar hydraulic system a little, very interesting.

It has a hydraulic "comparator". Can't remember the exact nomenclature for the system, but it compares the extension levels on both sides and matches them up hydraulically and very precisely. It is possible that this unit can fail, but it's probably some other fault.

As an anecdote, I know they landed the plane safely with a split flap scenario during FAA certification.

There is no interconnect between the flaps on the Aerostar, uses a calibrated orifice in each line that meters the hyd fluid to each flap. System works well.