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Partial Gear Retraction on Takeoff


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Went flying today with the objective to go get dinner on St. Simons island with my better half. It had been about 20 days since I had last flown my 71E as I have been split between Boston and Atlanta as I relocate. Conducted a preflight and I lubricated all exposed rod ends and bearings on the flight controls, flaps and gear linkages. (I do this about every 30 days) On preflight, nothing jumped out at me other then the battery was at 11.6 volts, however, the engine started after about 8 blades. After taxi and runup, my voltage was showing 14.1 with the amp meter showing a slight charge but where I expect it to be for takeoff. DA was 2600 feet, rotated at 68 MPH, once I had positive rate of climb, no useable runway and I push through 80 MPH, I selected the gear UP. I got the airspeed switch driven warning which normally clears itself at 88 MPH. After about 1 second, the gear warning horn silenced as I reached 89 MPH and the gear down light went out, I pitched for 87 MPH. About 3 seconds later, I was clear of the trees at the end of the runway, I pushed the nose down to try hit Vy at 108 MPH but this yielded a vertical speed of 0. Verified full power and good MP. Checked to see if flaps were up and they were. This left the gear which was now showing down from both the annunciator light and the physical indicator but had been selected up. I happened to have a friend flying in the area who I called over to check the gear and he indicated the mains looked down but the nose did not seem fully extended. I ran the emergency gear extension checklist and I got 2.5 pulls of the rip cord until I hit the stop with no change in the gear down annunciation. We then landed with out issue.

After talking about it with my better half, who happens to be an electrical engineer, we couldn't seem to come to an agreement point on where to start diagnosing this issue. Her theory is the battery is bad and the combination of charging the battery, cycling the gear and flaps meant that the alternator could not keep up. I don't disagree, but I pointed my finger at the newly installed airspeed switch, I have to accelerate past Vx to get the gear to come up and wait while the gear comes up before I can climb at best angle. I also have not been happy that my airspeed switch does not have an override button which the Maxwell's claim it doesn't need one. They claim the button is only for squat switch equipped airplanes, however the only time I have ever seen the button is in post 1978 J models. (Which should have the same airspeed switch I have in my E)

I am looking for any thoughts, comments or ideas what would cause the gear to not come up on departure. It may from something I caused by not waiting until I had cleared the airspeed switch speed before selecting gear up. I also will note, I normally fly with a gopro, however, on this day, my Gopros ended up in Boston, my plane in Atlanta... 

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1 hour ago, AerostarDriver said:

Went flying today with the objective to go get dinner on St. Simons island with my better half. It had been about 20 days since I had last flown my 71E as I have been split between Boston and Atlanta as I relocate. Conducted a preflight and I lubricated all exposed rod ends and bearings on the flight controls, flaps and gear linkages. (I do this about every 30 days) On preflight, nothing jumped out at me other then the battery was at 11.6 volts, however, the engine started after about 8 blades. After taxi and runup, my voltage was showing 14.1 with the amp meter showing a slight charge but where I expect it to be for takeoff. DA was 2600 feet, rotated at 68 MPH, once I had positive rate of climb, no useable runway and I push through 80 MPH, I selected the gear UP. I got the airspeed switch driven warning which normally clears itself at 88 MPH. After about 1 second, the gear warning horn silenced as I reached 89 MPH and the gear down light went out, I pitched for 87 MPH. About 3 seconds later, I was clear of the trees at the end of the runway, I pushed the nose down to try hit Vy at 108 MPH but this yielded a vertical speed of 0. Verified full power and good MP. Checked to see if flaps were up and they were. This left the gear which was now showing down from both the annunciator light and the physical indicator but had been selected up. I happened to have a friend flying in the area who I called over to check the gear and he indicated the mains looked down but the nose did not seem fully extended. I ran the emergency gear extension checklist and I got 2.5 pulls of the rip cord until I hit the stop with no change in the gear down annunciation. We then landed with out issue.

After talking about it with my better half, who happens to be an electrical engineer, we couldn't seem to come to an agreement point on where to start diagnosing this issue. Her theory is the battery is bad and the combination of charging the battery, cycling the gear and flaps meant that the alternator could not keep up. I don't disagree, but I pointed my finger at the newly installed airspeed switch, I have to accelerate past Vx to get the gear to come up and wait while the gear comes up before I can climb at best angle. I also have not been happy that my airspeed switch does not have an override button which the Maxwell's claim it doesn't need one. They claim the button is only for squat switch equipped airplanes, however the only time I have ever seen the button is in post 1978 J models. (Which should have the same airspeed switch I have in my E)

I am looking for any thoughts, comments or ideas what would cause the gear to not come up on departure. It may from something I caused by not waiting until I had cleared the airspeed switch speed before selecting gear up. I also will note, I normally fly with a gopro, however, on this day, my Gopros ended up in Boston, my plane in Atlanta... 

I'm not a mechanic, but I've recently had to remove and service my airspeed safety switch.  After reinstallation, it had to be readjusted.  On the VEP switches, there's a big slotted adjustment screw.  If the plane is on jacks, you can apply pitot pressure, look at the airspeed indicator, observe what speed the gear will retract and adjust from there. There may be more sophisticated procedures but this worked for me.  That may not be your problem though based on your description.  I checked my notes, and my switch is supposed to be set to 69 +/- 5 mph or 2.8 +/- .4" water.  It's designed to operate with increasing airspeed.  It may not deactivate at the same speed when decreasing pressure.  You've gotta test it with increasing pressure.  If your M20E is like my M20F, it didn't come with an override button.  I kinda like the idea but it defeats the purpose of the safety switch if you leave it in the wrong position.  

I flight tested my switch yesterday, and confirmed that I can get the gear up at 80 mph.  I didn't test it any slower than that.  

 

Edited by DCarlton
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If it’s the airspeed switch, absolutely nothing should happen when you select gear up.  Sounds like you had lights change and gear move?  I do agree with jacking it up and checking, but if the gear lights changed, it shouldn’t be the asss.  I don’t think the alternator/battery will do that either…. So good luck?  Maybe checking the limit switches? The gear electrical system is not complicated, but getting to each part and coming up with a good troubleshooting plan takes some time.  The motor, limit switches, asss, and connections are all in different (hidden) places.

Edited by Ragsf15e
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On my 69F, gear speed was approx 70 mph.  I had a density altitude situation once and finally got enough airspeed to retract the gear. 
 

There is a service bulletin to install a bypass switch, Lasar completed this for me.   I sold the plane so I don’t remember which service bulletin.

 

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1 hour ago, Ragsf15e said:

If it’s the airspeed switch, absolutely nothing should happen when you select gear up.  Sounds like you had lights change and gear move?  I do agree with jacking it up and checking, but if the gear lights changed, it shouldn’t be the asss.  I don’t think the alternator/battery will do that either…. So good luck?  Maybe checking the limit switches? The gear electrical system is not complicated, but getting to each part and coming up with a good troubleshooting plan takes some time.  The motor, limit switches, asss, and connections are all in different (hidden) places.

Part of the issue is I don't remember exactly what happen, I remember the green light going out when I selected the gear up. However, when I came back to it the green light was back on. I treated it as if I was not 100% sure the gear was down so I did the manual extension which I got two and half pulls out of it so I assume their was some gear movement.  

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51 minutes ago, Ron McBride said:

On my 69F, gear speed was approx 70 mph.  I had a density altitude situation once and finally got enough airspeed to retract the gear. 
 

There is a service bulletin to install a bypass switch, Lasar completed this for me.   I sold the plane so I don’t remember which service bulletin.

 

The SB is 20-196A which is only on the squat switch M20s.

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11 minutes ago, AerostarDriver said:

Part of the issue is I don't remember exactly what happen, I remember the green light going out when I selected the gear up. However, when I came back to it the green light was back on. I treated it as if I was not 100% sure the gear was down so I did the manual extension which I got two and half pulls out of it so I assume their was some gear movement.  

Seems like you need to put it on jacks, and cycle it while carefully observing behavior.  And you can check the setting on your safety switch and charge the battery.  But I'm not a mechanic; just a guy that just went through similar troubleshooting.  I believe the limit switches are all easy to locate and accessible from the belly pan.  

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When the motor stops during a cycle, either the motor died or it's not getting power. Usual causes for not getting power is airspeed switch, gear up/down limit switches or popped breaker.

When an airspeed switch is installed, it should be tested and adjusted if necessary per the procedure in the Service Manual.

While not required for your model, a gear safety bypass switch is a good idea. Everything after about 1978 has it.

The only safe way to troubleshoot gear problems is on jacks.

Good luck.

Skip

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1 hour ago, Yetti said:

Replace Circuit Breaker.  Grease Actuator.  What did you change last?

In November of last year the emergency extension clutch was replaced but the back clutch spring was retained. The airspeed switch was installed at the same time when the squat switch was found to be defective. Not related to the gear I added dual G5s, a GI-275, an AV-20S and removed the vacuum pump in April. During this I also replaced the alternator breaker as it had split in half.

1 hour ago, Ron McBride said:

Mine was wired to bypass the airspeed switch. 
 

I would prefer to have the override switch. Departing Northeast out of my home airport requires me to clear rising terrain, on a hot day I need all the help I can get.

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2 minutes ago, PT20J said:

When the motor stops during a cycle, either the motor died or it's not getting power. Usual causes for not getting power is airspeed switch, gear up/down limit switches or popped breaker.

When an airspeed switch is installed, it should be tested and adjusted if necessary per the procedure in the Service Manual.

While not required for your model, a gear safety bypass switch is a good idea. Everything after about 1978 has it.

The only safe way to troubleshoot gear problems is on jacks.

Good luck.

Skip

I figured the airspeed switch had been adjusted correctly as it was installed a DMax's. However, after going and re-reading the SB my airspeed switch is currently set way to high.

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16 minutes ago, AerostarDriver said:

I figured the airspeed switch had been adjusted correctly as it was installed a DMax's. However, after going and re-reading the SB my airspeed switch is currently set way to high.

You should never need the safety bypass switch in normal operation. For instance, In my M20J the airspeed switch is supposed to be set to 60 KIAS and Vx is 66 KIAS.

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23 minutes ago, AerostarDriver said:

In November of last year the emergency extension clutch was replaced but the back clutch spring was retained. The airspeed switch was installed at the same time when the squat switch was found to be defective. Not related to the gear I added dual G5s, a GI-275, an AV-20S and removed the vacuum pump in April. During this I also replaced the alternator breaker as it had split in half.

I would prefer to have the override switch. Departing Northeast out of my home airport requires me to clear rising terrain, on a hot day I need all the help I can get.

You're gonna talk me in to one.   It would be really easy to install.  How one gets approval for it if it didn't have it originally, I have no idea.  

Edited by DCarlton
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You say you are trying to clear terrain, but you seem to be leaving the drag down.   I was taught.  Lift off, Gear up, dip the nose for a few moments to gain speed get the wing flying then climb out.   By a Mooney Safety instructor.

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2 hours ago, Yetti said:

You say you are trying to clear terrain, but you seem to be leaving the drag down.   I was taught.  Lift off, Gear up, dip the nose for a few moments to gain speed get the wing flying then climb out.   By a Mooney Safety instructor.

Quite the contrary, normally, I have the plane cleaned up as quickly as possible. In the case in regards to this thread, the gear was stuck down. I was taught to fly the the airplane off using a little back pressure, accel in ground effect with the gear down, establish positive rate (at Vx) and with no effective runway remaining gear up. Once clear of the trees or anything else pitch Vy and flaps up.

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15 hours ago, AerostarDriver said:

Quite the contrary, normally, I have the plane cleaned up as quickly as possible. In the case in regards to this thread, the gear was stuck down. I was taught to fly the the airplane off using a little back pressure, accel in ground effect with the gear down, establish positive rate (at Vx) and with no effective runway remaining gear up. Once clear of the trees or anything else pitch Vy and flaps up.

If you are leaving the gear down till the end of the runway you are leaving alot of drag down.   The theory is if the gear comes up right after lift off you will have more speed and altitude which gives you more options.   We may be saying the same thing depending on what you define as effective runway.

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Different airplane, but I had a similar occurrence with a C-210 as in really low battery, we jumped it off and I took off, about 1 sec after I put the gear switch up. I had a total electrical failure. As you postulate the combined load of battery charging and the sudden additional gear load way overwhelmed the alternator, I don’t think a CB popped but I lost the radios etc.

So, I’m thinking as you apparently didn’t suffer any other electrical failures that you did not pull more power than the alternator / battery could provide.

‘My SWAG is as your having to accelerate after takeoff to get the gear to work due to the A/S safety switch, and that’s not normal, that the switch is most likely your problem.

Curious though, without a bypass how do you test the gear on jacks?

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3 hours ago, Yetti said:

If you are leaving the gear down till the end of the runway you are leaving alot of drag down.   The theory is if the gear comes up right after lift off you will have more speed and altitude which gives you more options.   We may be saying the same thing depending on what you define as effective runway.

Not until the end of the runway, just until there is no usable runway remaining. On the 3700 foot strip I fly out of, that is at rotation. My approach comes from how I have staged my abort criteria. Once the gear comes up I have effectively committed to flying, that means any problem from that point forward leads to landing straight ahead or entering the pattern to return to a normal landing. On a 6000 foot runway the gear will normally remain down until the halfway point, on short runways the gear comes up sooner. I may be wrong in that interpretation but if the engine quits and I have runway ahead of me, the gear and the drag are already there to help me make it. 

Edited by AerostarDriver
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1 hour ago, A64Pilot said:

Different airplane, but I had a similar occurrence with a C-210 as in really low battery, we jumped it off and I took off, about 1 sec after I put the gear switch up. I had a total electrical failure. As you postulate the combined load of battery charging and the sudden additional gear load way overwhelmed the alternator, I don’t think a CB popped but I lost the radios etc.

So, I’m thinking as you apparently didn’t suffer any other electrical failures that you did not pull more power than the alternator / battery could provide.

‘My SWAG is as your having to accelerate after takeoff to get the gear to work due to the A/S safety switch, and that’s not normal, that the switch is most likely your problem.

Curious though, without a bypass how do you test the gear on jacks?

I happened to pull the G5 log and found that at the time I retracted the gear I lost the GAD 13 and GMU 11 which puts more weight in the electrical load too high category.

After talking it over with my A&P we are going to cycle the gear on Jacks. Likely replace the battery as it's probably time. Adjust the airspeed switch and re lube everything for good measure. 

Thanks for the help guys!

Edited by AerostarDriver
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3 hours ago, AerostarDriver said:

Not until the end of the runway, just until there is no usable runway remaining. On the 3700 foot strip I fly out of, that is at rotation. My approach comes from how I have staged my abort criteria. Once the gear comes up I have effectively committed to flying, that means any problem from that point forward leads to landing straight ahead or entering the pattern to return to a normal landing. On a 6000 foot runway the gear will normally remain down until the halfway point, on short runways the gear comes up sooner. I may be wrong in that interpretation but if the engine quits and I have runway ahead of me, the gear and the drag are already there to help me make it. 

At the 3000' strip I was based out of my first 7 years, my C was at least 250 agl at the end, getting down and stopped if there was another 3000' in front of me would be difficult. Just like my Owners Manual says, positive rate and in good control, gear up. That's usually around treetop level or just above. She accelerates much better gear up, I hold Vx (85 mph) until I'm above everything out front then lower the nose and accelerate to Vy (100 mph).

Of course, if I left the gear down, I'd be much lower at the 3000' mark and maybe could get down and stopped in the next 3000 feet . . . .

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Swing the gear on jacks, then woop out the voltmeter :-) I’ll suspect the brushes on your electric motor are worn. This happened to me recently. I have a spare good one I’ll sell you if that’s the case.  it could also be one of the two solenoids that drive the gear motor or a limit switch. The schematics shouldn’t be hard to find. I have them.

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