Delayed "Gear Unsafe" Light extinguish on Gear Up

[MisfitSELF]

Please direct this to the appropriate thread if there is one but I couldn't find one...

Recently purchase a M20J -- LOVE IT!   However, on about 3 or 4 of my take off in the last 2 months since I've bought it, I've noticed that the "Gear Unsafe" light seems to stay on a few seconds longer than what I (with my whole 10 hours of Mooney time...) would consider normal.  It eventually goes out, but I'm not sure why.  I've found myself making "really" sure that the landing gear handle is "REALLY" up by pulling it out and wiggling it and then making "REALLY" sure about 2 or three times that it is "REALLY" in the UP position.  Meanwhile I've checked the indicator between the seats and it shows the "red, hey, idiot, the gear is up" indication.  And about then, the light goes out.

Note that most of the time the "gear up cycle" is about what I'd expect in my 400+ hours of retract time (granted only 10ish hours in the Mooney).  It goes like this:  move the gear handle up, hear noises for about 5ish seconds, hear a "klunk", see lights or indicators change from "gear down" to "gear up", the end.  My Mooney, does the same thing, most of the time.  It's just about 3 times now it's done what was described in the first paragraph -- or in other words a delayed gear up indication.

Additional notes, I find that I'm fairly consistent:  at 80 - 85 knots with positive rate and no more usable runway, I'm selecting gear up.  I know for a fact I'm not over speeding the gear when this happens nor have I ever over-sped the gear going up or down.

Does anybody have any insight as to what may be going on?  Is this normal?

 

[jasona900]

Unsure what the issue is, but would probably be best to put it on jacks and swing the gear.  Make sure you read up on the proper jacking procedures for a Mooney if you aren't already familiar...a quick search on this site and the assistance of an A&P will help... and welcome!

[N201MKTurbo]

Does the motor keep running the whole time? Do you notice the ampmeter reading real high? 

[carusoam]

The unsafe light is on while the gear is traveling...

How long is your light staying on, longer than 10 seconds?

You can Compare the light with the gear position indicator in the floor.  Are you seeing a barber pole indication with the light on?

PP thoughts only, not a mechanic...

Best regards,

-a-

[N9201A]

You don't say what year your J is, but the 14V ships retract their gear more slowly than the later 28V ships.  You also haven't said how "long" is "too long"...compared to what? 

[carusoam]

Now that 201A has mentioned time.... do you have the 20:1 or the 40:1 gear set for the landing gear?  One is much quicker than the other.

Best regards,

-a-

[MisfitSELF]

Really I was fishing to see if there was already a thread for this but now it sounds like I need to run down some more info.  So far my assessment of "slow" is entirely qualitative as my very few data points have been during climb out.  I can't say for sure that the barber pole indicator deviates from the light as the light is out by the time eyes sweep from looking down to up at the lights.  Also note, everything "feels and looks" right when lowering the gear and "feels and looks" right most of the time when raising the gear.

What I can say now is that my 20J is a 1984 with a 12V electrical system.  Next time I'm up and away, I'll try some gear swings and time them.

[carusoam]

Can you feel the gear thump as it gets locked in place at the end of its travel?

Some backsides are more sensitive than others(?)...

PP thoughts only, not a CFI or mechanic...

Best regards,

-a-

[TTaylor]

The early J's had  20:1 gear drive, later and updated had 40:1. Need to confirm if the gear is up and the light is slow or that the gear is just slow.

    One thought is that the gear doughnuts are old.  This usually causes problems with gear sensors in the winter but if very old may cause problems in the summer.

[Yetti]

There are two switches along one of of the rods. Just left of center to the rear.  Might want to wash them out with some contact cleaner.  There is also a brake on the motor that might not be holding causing the motor to run more to keep the gear up.

Here is a video of the gear working.

 

[N201MKTurbo]

59 minutes ago, Yetti said:

There are two switches along one of of the rods. Just left of center to the rear.  Might want to wash them out with some contact cleaner.  There is also a brake on the motor that might not be holding causing the motor to run more to keep the gear up.

Here is a video of the gear working.

 

That is a nice clean belly you have there!

[Guitarmaster]

Does your airplane have a squat switch or an air speed switch? If you have a squat switch, I would look at the adjustment of the squat switch and the condition of your Donuts.

As somebody else said, it's usually a winter problem but if your Donuts are bad enough it could present itself in the summer as well.

I would suggest putting it up on Jacks, at least left landing gear, and see if there is any movement fore and aft. This was the problem with mine.

 

 

Sent from my XT1585 using Tapatalk

 

This is a video of the slop in mine when cold. The clicking is squat switch activating and deactivating. Although it does need replacement Donuts in short order, I solved the problem by moving the squat swhich about an eighth of an inch closer to the pressure plate.

 

https://goo.gl/photos/ME4QqBVc5Lm8xbB78

[anthonydesmet]

I am almost sure you have an airspeed switch behind your airspeed indicator and not a squat switch. I can try and find when the switches changed but I know mine is an airspeed switch and I think it happened with J and K models around 1981ish.  If you have the airspeed switch you are getting the red unsafe light with warning tone because you are below the airspeed the switch is set for with the gear handle in the up position.  The switch is giving you the tone because you are in proximity of landing speed with the gear handle in the wrong (up) position.  It's saying "hey dummy (that's what mine calls me) you are trying to land without putting the gear handle down".  This is because the switch references the handle location and not the gear location.  Before I would try all this good advice I would fly a couple of times and refrain from putting the handle up until your at 85kts and accelerating just to give you a couple knots of cushion.  I think mine is set around 82kts and in my service manual ref's 80 to 85 kts so yours maybe a little higher.

if i'm wrong there is plenty of great advice and education in the posts above.  Good luck and please let us know......also welcome to Mooney ownership......great airplanes but sometimes....#@!!

[anthonydesmet]

All, reading through my last post I may have mis-led a little.  The airspeed switch and squat switch's entire purpose is to prevent inadvertent gear up on deck. That's why the gear is taking so long to raise becaus you are not above minimum airspeed.....I know, duh.  the throttle position resulting in MP while airborne and gear not down will give you the gear horn to lower the gear.  In either case it's a "hey dummy, check the handle" because it doesn't agree with where the airplane is.

[MisfitSELF]

Got a chance to fly this weekend and collect some additional data.  After referencing the MX manual, I "discovered" there is indeed an airspeed component to my issue via the airspeed switch reference above.  I now believe I was simply too slow when I attempted to raise the gear before.  Not slow enough for the tone or for it to prevent the retraction but perhaps slow enough to cause it some issues with the indications or the drive motor.

So here's what I did:  I performed several gear cycles up and away at varying "slow speeds"  Unfortunately none of them replicated what I subjectively observed before (perhaps a 'good thing'?)

Set up 6500 to 7000 MSL (4000 AGL)

1.  75 knots, flaps T/O (15deg),  gear extension normal, gear retraction normal -- ~4.5 to 5 secs for the light to extinguish

2. 70 knots, flaps landing, gear extension normal, gear retraction normal -- ~ 4.5 to 5 seconds for the light to exitinguish, retracted the gear at around 70-75 knots -- normal operation.  I believe it was near 70 knots where I got the landing gear tone when gear up.

3. 65 knots, flaps landing (33deg), gear up with landing gear tone -- lowered gear, normal operations,  went to raise the gear and it didn't function.  Now I had the "gear unsafe light" and the "gear down" illuminated.  The gear remained down as verified in the window with the gear handle up.  Then I lowered the gear handle and the tone stop and the "gear unsafe light" extinguished.  "Gear Down" light remained illuminated

4.  I sped up, raised the gear -- normal operations observed. 

5.  Slowed to ~60knots.  Had both the stall warning and gear tones (it at least sounded like it was trying to give me two different tones).  Lowered the gear, stall warning tone remained.  Otherwise normal.

6.  Finally, raised the gear handle same result as step 3

7.  I then sped up to see where the gear would come up and it was about 75-80 knots.

Thus I suspect that the airspeed switch is the probable cause of my observations in my OP.  Also, ironically, I did not experience what I observed before on the take off for this sortie.  Granted it only happened about 20-30% of the time but I was more "anal" if you will about not selecting gear up until I had like 80-85 knots.

Bruce

[carusoam]

Great details, Bruce...

Best regards,

-a-

[anthonydesmet]

Bruce,

concur, great details.  

Point number 3 - "Now I had the "gear unsafe light" and the "gear down" illuminated.  The gear remained down as verified in the window with the gear handle up.  Then I lowered the gear handle and the tone stop and the "gear unsafe light" extinguished.  "Gear Down" light remained illuminated"

you didn't mention if you think you still have a problem but i dont think you do. Your indications are normal I think.  

Remember though, " 65 knots, flaps landing (33deg), gear up with landing gear tone" - the landing tone is coming from where your throttle position is and resultant manifold pressure not the airspeed switch.

If your interested here are a couple excerpts from the maintenance manual:

LANDING GEAR WARNING SYSTEM.

The landing gear warning system provides the pilot with an audible warning that the landing gear is not down and locked when the throttle is retarded below 10 inches manifold pressure on SIN 25-0001 thru 25-0780. The warning system on aircraft SIN 25-0781 & ON is activated when the throttle is retarded below 16 to 18 inches MP. When the landing gear is down and locked the electrical circuit is opened and the intermittent horn is stopped. This warning switch is mounted on the throttle housing forward of the instrument panel and can be adjusted for the proper setting by loosening the screw and repositioning the switch.

    

32-30-00 32-30-01

- EXTENSION AND RETRACTION

- GEAR SYSTEM OPERATIONAL INSPECTION

1. Raise aircraft on jacks. (See Section 7-10-00).
2. With Master Switch ON and gear switch in UP position, apply pressure to pitot tube (see Section 32- 60-01). Verify gear retraction occurs at 75 MPH +/- 5 MPH (65 +7/-4 KIAS). Allow gear to raise completely.

Check for any tire interference as tire enters wheelwell.

3. Close throttle and confirm gear horn sounds........etc, etc, etc

 

 

like I mentioned before, mine likes 80+ knots.  I am going into annual in a couple,of weeks and I can see if the airspeed switch is something that is adjustable because that I am not sure of....maybe someone else knows.