Landing Gear Failure To Extend

[Skyatty]

I had an interesting morning this morning.  I went up with an instructor to do some airwork and landing practice.  We finished the first landing and were in the downwind for the second.  I put the landing gear lever in the gear down position and . . . nothing.  Sat staring at the blank indicators for a second then slowly cycled the switch . . . nothing.  No sound, no light, no movement, no change in the floor indicator.  Nothing.  We left the pattern and flew around trying to troubleshoot.  Breakers were seated, electrical power seemed fine, no other indications of trouble but no gear.  Cycled through two more times and still no gear.  We discussed it for a moment and then, with nothing better to do, I cycled it one more time.  Nothing for a second then suddenly the lights came on, the motor worked and the gear was down.  Gear down light green and the floor indicator indicated gear down.  Flew back to base with the gear down at the speed of a 172 and landed uneventfully.  Plane will go to maintenance Monday for examination.  Anyone else experience anything similar?

[Piloto]

Did you check the emergency extension lever between the seats. If not properly latch in place the gear will not actuate. Sometimes passengers in the rear seat may accidentaly unlatch the lever with their feet. The lever is used to secure the cable pulling handle and to release the motor clutch.

José 

[Skywarrior]

Hmmm... the events between the first gear-down event and the gear-no-workee event were a touchdown and a successful retraction (I'm assuming).

(If you're a Monty Python & The Holy Grail fan, you'll appreciate this.)

"So...logically..."

...something about either the landing or the subsequent retraction is probably associated with the root cause of this.

Like, maybe the landing impact (even as baby-soft as I'm certain it was) shook something loose. Heck, it may even be something as small as a loose wire or a bad gear switch on the panel.

Please update all of us when you discover the cause.

 

Chuck M.

[Scott Aviation]

77 201 SN 0185 will have the dukes gear actuator and hand crank in the cabin, so there will be no issue with that causing it to not retract, the only thing it would do is bind against the clutch if the gear down was activated while the emergency crank was engaged.  You have a squat switch on the left main gear but that is for gear failing to retract.  So thats not the issue.  A failure to extend the gear I would say most likely resides with the gear switch itself, or a loose wire in the connections, I would also check the cannon plugs that run from the gear actuator to the relays for corrosion.  Im just reviewing the electrical schematic for your sn and its such a basic circuit, really its probably a bad contact in the gear switch or a loose connection from there to the gear relays.  Hope this helps clarify good luck

[Scott Aviation]

Here are 3 drawings of the applicable landing gear circuit for your aircraft, I've highlighted a few areas to look at.  Sorry I left off the squat switch and landing gear horn.  But as I said before they will not effect a gear down from happening.

Hope these help.

[jelswick]

On the gear actuator and emergency gear extension lever Jose mentioned, I just spent $206 only a month ago to learn more about that system (maintenance troubleshooting before determining that was the issue).  I'd taken off with my son in the co-pilot seat and apparently he may have bumped it when fastening his seat belt, but it came loose and in troubleshooting why my gear would not come up, that was not included because I didn't realize the relationship I now know about between taking that cover out of the precariously locked position engages a clutch that will prevent the gear actuator from working and pops the circuit breaker if you try.  Luckily, mine was a gear stuck down issue rather than stuck up, but either way, that was an expensive way to learn more about that system.  Could have been worse, so no complaints, but that was a tank of fuel spent on the lesson.

[davbert]

I had this happen several months ago.  It occurred after I installed a JPI 700.  There is a connector behind the panel for the gear switch. I found it loose due to manipulating the wiring behind the panel during the install.  Tightening the connector fixed the problem.

[Jeff_S]

I was going to suggest that it was a sneaky instructor testing you on this emergency procedure, but from your description it sounds like he wasn't in on the prank. Glad to know things worked out.

[Skyatty]

Scott, thanks for all the information.  I am thinking it is a switch issue.  Just prior to putting the switch in the down position, I tried twisting it very lightly hoping it might be a connection issue and a moment later the gear finally triggered and came down.  Actually, the landing before was one of my best ever; an FAA inspector who happened to be trailing us in the pattern even remarked "excellent landing" after touchdown, so I don't think I jarred anything loose.  

We had a particularly tough winter up here and I have not flown the plane since late October due to relatively constant storms every three to four days and freezing levels to the surface; that's why I was with the instructor - shake off some rust and do some basic airwork.  Two weeks before that last flight, I had a radio repaired and it makes sense that a connector may not have been seated fully.  Will hopefully know on Monday afternoon and will let the board know.  Jose, I do not believe that I have the switch that you refer to.  Thanks everyone and Happy Father's Day.

[Skyatty]

Still waiting for maintenance report but my cousin sent me the following link:  http://www.moapilot.com/pdf/March06/March06web.pdf

[KSMooniac]

Your exact problem happened to me in 2008, and it turned out to be a worn-out gear motor.  If your motor has never been out of the plane, I would remove it for an inspection at the very least, but plan for an overhaul.  There is a shop in CA that is a favorite of LASAR and Willmar that will do it for a reasonable sum.  Good luck!

[Skyatty]

Update:  The mechanics went over the gear and could not replicate the problem (as in the article above).  They found that one of the rods was out of spec and adjusted it and thought that might have been the problem, but everything else appears solid.  They also cleaned the gear switch just in case.  Cycled the gear many times and it seems to work fine.  I believe that I will study the manual extension procedure several times and have the checklist close at hand.  Sigh.

[rorythedog]

i've had the the gear fail to retract once....it was on a moonless and black night.  i figured out that a backseat passenger had inadvertantly unlatched the emergency handle, but it was an anxious 10 minutes or so......  

[KSMooniac]

Definitely study the manual extension checklist, and make DAMN SURE the manual system is rigged correctly...there are some failure modes due to rigging that can leave the gear locked up...hopefully your shop knows this.

[KSMooniac]

Also, the motor could still be questionable IMO.  It might have enough capacity to move the gear on jacks, but not with air loads on the wheels/doors.

[N33GG]

There is nothing more frustrating that a gear problem that has revealed itself briefly, gone into hiding, and is lurking and waiting to strike.

Murphy's Law for this case:  The gear will fail to extend at the worst possible time when you really need it to work right.

I have been there, a couple of times.  Good luck!

[Parker_Woodruff]

Please be sure to verify gear down by lights and the mechanical indicator, especially in the near future.  There can't be anything worse than putting the gear switch in the correct position, and not realizing that the gear didn't come down.

[jetdriven]

Thankfully in the Mooney the gear motor is bolted to the underside of the seat rail, and makes the seat twist in the plane when going up or down.  Excellent "seat of the pants" reminder that your gear is in transit.

[Skyatty]

Parker, yep, I've made that a habit since I got the plane but I sure hate where they put the indicator - PITA to see.  Scott, if it is the motor, I'm not sure what to do about it - would you guys replace or overhaul a gear motor in this instance as a precaution?  I think I'll give Don Maxwell a call on Monday and get his thoughts.  By the way George, my cousin lives in Palestine - beautiful place and the lake is gorgeous from the air.

[roundout]

Quote: Skyatty

Actually, the landing before was one of my best ever; an FAA inspector who happened to be trailing us in the pattern even remarked "excellent landing" after touchdown, so I don't think I jarred anything loose.  

 

[David Mazer]

I had an intermitent gear problem on my experimental airplane (a SeaRey).  It took many attempts to figure out what the problem was and I had to manual reach out and hit my left main with my hand to get it started several times (not as hard to do as it sounds).  It made me very uncomfortable having checked it on the ground over and over with no ability to recreate it.  Finally, it turned out to be a tiny dead spot in the electric gear actuator and when the gear stopped in the up position at that tiny spot, it wouldn't go down until I found a way to get it off the dead spot (hitting it with my hand, for example).  The manufacturer of the plane kept saying it wasn't the actuator since they had never had a failure with one before until the problem occured at their lake and they were there to help me out.  There is, apparently, a first for just about everything.  I replaced the actuator and haven't had a problem since.  I suggest you don't give up trying to diagnose the problem as the gear really isn't a system I like to be paranoid about and, I suspect, you don't either.

[140pilot]

I had the same issue occur when I had my 78 20C. Coming in for landing hit the gear switch and nothing. Circiled the field and did the same trouble shooting procedures and finally on my last try I cycled the switch and the gear came down. My AP and I jacked up the plane and checked the motor, circuits, wiring, switch and then cycled the gear numerous times with no issues. While I had the aircraft on the jacks I practiced hand cranking down the gear and making sure everything worked properly.

I then flew another 20 trouble free hours. Then coming into Goldsboro NC I hit the gear switch and again nothing. This time it was not going to come down so I climbed to 4k feet and cranked the gear down by hand. Made an uneventful landing. Turns out the gear motor had an internal intermittant problem. AP installed a rebuilt motor and I was on my way a couple days later.

If you have the chance to practice dropping the gear down using the hand crank do so. I am glad the first time using the system was not while flying the aircraft.

[bronzburg1]

Where is the gear down relay located?

[bronzburg1]

My Gear intermittedly does'nt go down (comes up fine), but when I manually put them down; works for a while then out of the blue wont extend. Then motor is rebuilt, according to my logs, but dont see where relays were replaced; so I was going to try that. All safety switches and lights seem to be operating normal. Thanks for any suggestions.

[ghovey]

My gear does the same sort of thing, only there is a delay sometimes and then it goes down or I cycle the switch and it usually works, occasionally I have given it a little gravity help by quick nose up, checked thoroughly by a&p and no idea other than internal gear motor issue. Manual works fine.