Gear retract delay on 70C

[tcal780]

Hello all,

Just got my 70C back from annual and the gear won't go up below 70KTS. I know there's an airspeed switch that won't allow it to retract without input from pitot, but as long as I'm positive rate, I want to be able to bring em up if I need to.

Is this an adjustable parameter or does this switch need to be replaced? If replacement is needed, what are my chances of keeping my 1st born?

Best,

tcal

[MBDiagMan]

The airspeed switch disallows gear retraction below about 80 knots.  I may be wrong on the exact speed, but the switch is in series with the gear up circuit.  The switch is near the altimeter.  Different year models were different, so it could be that yours has a squat switch instead that is misbehaving.  It’s spelled out well in the maintenance manuals.  It’s been a long time since I had to mess with it, so details are foggy in my ancient brain.

I guess you are needing the gear up slower due to short field operation?

Edit:  I have a copy of the manual in my Foreflight documents.  I tried to copy the page to here with no success.  IIRC the manual is downloadable from this site.  Section 5 has the electric gear information.  It appears that the airspeed switch was used 1967 MY on.

Hope this helps.

Edited July 1, 2023 by MBDiagMan

[kortopates]

it’s much slower than 80 kts, my recollection in the mid and long bodies is about 60 or 65 kts +/- 5 kts, but the spec is in your models service manual. How to adjust is also covered in the SM.


Sent from my iPhone using Tapatalk

[MBDiagMan]

Mine may need adjusting then.  I went through gear troubles about five years ago and as I recall, it was clicking at 80 MPH.  That setting has never posed a problem for me, but then again, I’ve never taken off in less than 3,000 feet.

BTW, if you are going to adjust it, in a quiet hangar you can here it click when the pressure is high enough to actuate the contacts.

Hope this helps.

[MBDiagMan]

The note referred to on page 5-23 of the service manual specifies 80 MPH airspeed equivalent is the point at which the switch is supposed to actuate. 
 

Found it!

 

 

okay, the above manual only goes through 67 models, but it should be a good example of what to look for if you can find the same manual covering th 70 model.

Again, Hope this helps.

 

Edited July 2, 2023 by MBDiagMan

[MBDiagMan]

Okay, I think this one covers your model:

[Hank]

2 hours ago, MBDiagMan said:

Mine may need adjusting then.  I went through gear troubles about five years ago and as I recall, it was clicking at 80 MPH.  That setting has never posed a problem for me, but then again, I’ve never taken off in less than 3,000 feet.

Ground rolls in my 1970 C are generally less than 1000'; I've gone in and out of 2000' grass strips . . .

Except when heavy, takeoffs are no flaps and I rotate going through 70mph. Per the Owners Manual, "once in good control" I verify positive rate and raise the gear. As shown in the photo above, that's generally around treetop level, but I've not paid attention to the ASI when I do it. Guess I need to a couple of times, see what's going on. 

[MBDiagMan]

Do you have electric gear Frank?

[Hank]

2 hours ago, MBDiagMan said:

Do you have electric gear Frank?

All Mooneys built beginning with 1969 models are electric gear and flaps.

[Fritz1]

these switches wear out and they are expensive, I replaced mine when the TKS stall vane heat was on high continuously when the pitot heat was on, allegedly this is a sign of the gear air pressure safety switch failing soon thereafter, maybe switch can be overhauled, I would not attempt to adjust it

[MBDiagMan]

Five years ago, Paul Maxwell had a source for the diaphragm and rebuilt mine.  Don’t know if it’s still available or not.

[tcal780]

Thanks for the info.

MBDiagMan, I was unable to get that SM from the link you provided (the one that covers my 70C).

[MBDiagMan]

My mistake tcal.  It turned out to be a parts manual.  You can go to the Browse area on this Forum and download what manuals they have available.

[tcal780]

Thanks, I found it. Yes, The PDF filenames need to be swapped on those docs.

The adjustment process looks pretty straightforward and 80MPH is actually the upper limit.

[MBDiagMan]

Glad you found it tcal. Hope it gets you what you’re looking for.