Cessna 172 RG, GEAR Issue

smisek

smisek

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smisek
Anyone have input on why gear will not fully retract on a 1980 172 RG. Nose gear stows, right side stows, BUT the left side hangs down about 8-12 inches. Left side locks down properly, but even with slight help pushing up into wheel compartment does not go. No noises, no hard landings.

Just started. Was working fine until last cycle. 1000 hrs since left actuator was replaced, ADs done on checking gear in 2001.

:mad2:
Actuator, gear mechanism, both?

And I thought the radio was an important issue...

thank you.
 
oh ya, the hydraulic pump pressure is good....replaced that 2 times now in 6 months... so finally not an issue. wished they covered labor! not just parts
 
Check the teeth on the actuator, I repaired one once that had cracked the rack on the piston rod.
 
hindsight2020 said:
I need to sticky this thread for every time the retract cult around here try to tell me the extra gas burnt on welded gear *easily* exceeds gear maintenance and insurance for the year on anything single engine piston powered. :rolleyes:
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:yes::yeahthat::yes:
 
hindsight2020 said:
I need to sticky this thread for every time the retract cult around here try to tell me the extra gas burnt on welded gear *easily* exceeds gear maintenance and insurance for the year on anything single engine piston powered. :rolleyes:

Good luck on de-bugging that problem OP. That sounds like a huge hassle. Hope you get back in the air soon!
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Insurance really isn't a factor, especially on your typical 172RG. He has temporary issue, welded gear is permanent drag. And the RG mechanism on the Cessna singles is a bad implementation of the concept.

I could start a thread discussing the issues I've had. I'd be empty and you could bookmark it.
 
bartmc said:
Insurance really isn't a factor, especially on your typical 172RG. He has temporary issue, welded gear is permanent drag. And the RG mechanism on the Cessna singles is a bad implementation of the concept.

I could start a thread discussing the issues I've had. I'd be empty and you could bookmark it.
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Bart, to be fair, you really can't compare the robust and reliable Bonanza gear design with Cessna's rig (which, I admit, works better than you'd think, most of the time, based upon it's "ooh, something broke" appearance on retraction).

Come to think of it, I do believe that the Bonanza's gear is more reliable than the Cirrus'!
 
Cessna owners are always willing to discuss "robust" structural design problems with V-tail owners.

SCCutler said:
Bart, to be fair, you really can't compare the robust and reliable Bonanza gear design with Cessna's rig (which, I admit, works better than you'd think, most of the time, based upon it's "ooh, something broke" appearance on retraction).

Come to think of it, I do believe that the Bonanza's gear is more reliable than the Cirrus'!
Click to expand...
 
wabower said:
Cessna owners are always willing to discuss "robust" structural design problems with V-tail owners.
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I see you rectified the wrinkled firewall issue of the 182 and are skipping out on the hot hydraulic fluid shower of the 182RG by putting your wheel on the back. :D
 
Yep, just call it tangible evidence of my long-held belief that you gotta be smarter than what you're working with. :D

bartmc said:
I see you rectified the wrinkled firewall issue of the 182 and are skipping out on the hot hydraulic fluid shower of the 182RG by putting your wheel on the back. :D
Click to expand...
 
I really don't know either, but I was thinking some type of actuator. I know they wear out on the mooneys. In fact, a lot of owners switched the 20:1 with 40:1 actuators to put less stress on the system.
 
So the gear cycle properly, but the left will just not go all the way up? It sounds like you put it on jacks and tried to push it up right? If you cannot see it hitting anything, then disconnect the actuator and try and push it up. If it goes, most likely the issue is with your actuator. You should be able to verify this by manualy cycling the actuator by hand to see if there is some binding. That is where I would start. Let us know what you find out.
 
hindsight2020 said:
I need to sticky this thread for every time the retract cult around here try to tell me the extra gas burnt on welded gear *easily* exceeds gear maintenance and insurance for the year on anything single engine piston powered. :rolleyes:

Good luck on de-bugging that problem OP. That sounds like a huge hassle. Hope you get back in the air soon!
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Don't paint all retracts with the goofy cessna single gear. The Arrows and the Navion have dirt simple gear.
 
There is an SB on those actuators. The older ones crack and bind. Last I looked, that casting cost $8800.
 
Dan Thomas said:
There is an SB on those actuators. The older ones crack and bind. Last I looked, that casting cost $8800.
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I don't think that is incorrect. I have also been told that if the bolts attaching the actuators are kept torqued it helps prevent cracking.
 
Skylane81E said:
I don't think that is incorrect. I have also been told that if the bolts attaching the actuators are kept torqued it helps prevent cracking.
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Couple of must-reads on these things. I can't find an online copy of the SB 01-2. Cessna charges for that stuff. Anyway, the actuator housing tends to crack across the thin area around the rack roller and the whole thing can fail.

http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20031015X01735&ntsbno=LAX04LA011&akey=1

http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20090115X05748&ntsbno=WPR09LA083&akey=1

And those bolts: they're special AN174H-something high-strength bolts, and if one replaces them with AN bolts he's asking for trouble. Besides that, the actuator loads also try to rotate the actuator housing and that bends those bolts just a bit every time the gear is raised or lowered, and that cracks the thread roots of the bolts. I had one break off deep inside that heavy mounting casting that the whole airplane is built around, and was lucky enough to be able to use a mirror to see enough to drill it and extract it without either damaging the casting or having to take half the airframe apart to get it out. After that, it was brand-new bolts every time we worked on it.

There's another, newer SB that demands a check of the leg itself at the spline/bearing root radius. They tend to crack there, too, and losing brake fluid is an indication. The brake hydraulic pressure travels through that leg.

Dan
 
Service Bulletins, Letters etc are free to cessna owners who sign up (for free) at www.cessna.com btw


SEB90-1R3 - Main Landing Gear Pivot Inspection. Perform fluorescent pentetrant inspection and replace cracked pivots with new p/n 2441100-10. Inspection should be accomplished within the next 100 hours operation or annual inspection or if the brakes feel spongy, whichever occurs first. This part number lists for $5,501.70 at cessnaparts.com
Note Installation requires concurrent installation of SK172-151 which lists for $381.90

SEB01-2R2 Main Landing Gear Actuator Inspection - Perform a fluorescent penetrant inspection on actuator bodies and actuators, replaced cracked parts.
9882015-4 actuator $8,820

SNL86-49 - Main Landing Gear Actuator Mount Bolt Security - Drilled head bolt AN175H22A is an approved alternate for NAS464P5LA29 bolt. The AN175H22A bolt will allow safety wire and may be installed, as desired, or whenever loose actuator to pivot assembly bolts are detected.
 
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I would recommend that anyone installing a gear leg on a 172RG not buy the tool from Cessna, but have one made at a machine shop. I'm sure it would be much cheaper
 
smisek said:
Anyone have input on why gear will not fully retract on a 1980 172 RG. Nose gear stows, right side stows, BUT the left side hangs down about 8-12 inches. Left side locks down properly, but even with slight help pushing up into wheel compartment does not go. No noises, no hard landings.

Just started. Was working fine until last cycle. 1000 hrs since left actuator was replaced, ADs done on checking gear in 2001.

:mad2:
Actuator, gear mechanism, both?

And I thought the radio was an important issue...

thank you.
Click to expand...
Do you have a return line filter? for the up cycle it would be in the down pressure line.

it may be in the power pack. creating a restriction in the up return line holding the gear partially extended.
 
Tom-D said:
Do you have a return line filter? for the up cycle it would be in the down pressure line.

it may be in the power pack. creating a restriction in the up return line holding the gear partially extended.
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The only filter in that system is a tiny thing located in the powerpack, and it has a small relief valve in it in case it plugs.

Of course, there might be something else floating around in either hydraulic line that comes up against the fitting at the actuator or control valve and stops the flow, but I'd bet that there's an issue with that actuator. They are the weakest part of that whole design.

Dan
 
So. I dont or cant post pics, but look at my profile pic. That is the problem I found. A completely cracked actuator through both sides of the bolt hole. Guess that was the explosion/bang sound I heard in cruise flight while the gear was up.

Found out Cessna has had issues with these since 2001 or early on all 172/182/210 RGs since that is the date of the original SEB, then revised in 2007. Amazingly it looks like Cessna has done nothing to improve the part... just check it for cracks...and if its broke buy the same dang one again. That's right, they will just sell you another one with no improvement from know defects for a mere $9000 plus the standard one year warranty, which for most of us might be a 100-200 hrs in a year? Oh...and if you do look for cracks referenced in their service bulletin, it makes no mention of looking for cracks at the bolt holes, or other places, only near the piston shaft opening.

Funny thing both of the actuators on this plane (4300TT) were replaced approx 1000 hrs ago. So there's the life expectancy. Two of these every 1000 hrs is just about the cost of a new engine, what a deal.

Thank you Cessna. Waiting for them to reply after sending photos.....yeah right I'm just a one plane owner...
 
smisek said:
So. I dont or cant post pics, but look at my profile pic. That is the problem I found. A completely cracked actuator through both sides of the bolt hole. Guess that was the explosion/bang sound I heard in cruise flight while the gear was up.

Found out Cessna has had issues with these since 2001 or early on all 172/182/210 RGs since that is the date of the original SEB, then revised in 2007. Amazingly it looks like Cessna has done nothing to improve the part... just check it for cracks...and if its broke buy the same dang one again. That's right, they will just sell you another one with no improvement from know defects for a mere $9000 plus the standard one year warranty, which for most of us might be a 100-200 hrs in a year? Oh...and if you do look for cracks referenced in their service bulletin, it makes no mention of looking for cracks at the bolt holes, or other places, only near the piston shaft opening.

Funny thing both of the actuators on this plane (4300TT) were replaced approx 1000 hrs ago. So there's the life expectancy. Two of these every 1000 hrs is just about the cost of a new engine, what a deal.

Thank you Cessna. Waiting for them to reply after sending photos.....yeah right I'm just a one plane owner...
Click to expand...

Ouch!! :hairraise: scrap yard? Or is that just peeing money away?
 
smisek said:
So. I dont or cant post pics, but look at my profile pic...
Click to expand...

1lg019idea.gif


Then learn how to post pictures! Really, it's easy. One way:

#1 creat a free account at a place like photobucket.com
#2 upload pictures to that account
#3 paste the "image code" link directly into your posts on the forum.
 
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bartmc said:
Ouch!! :hairraise: scrap yard? Or is that just peeing money away?
Click to expand...

I got a steering bungee from a scrap yard because Cessna wanted $7000 and 3 or more months for one. I'd bet you can find an actuator for 3000 or less if you look.
 
bnt83 said:
1lg019idea.gif


Then learn how to post pictures! Really, it's easy. One way:

#1 creat a free account at a place like photobucket.com
#2 upload pictures to that account
#3 paste the "image code" link directly into your posts on the forum.
Click to expand...

He has a low post count. I don't think POA allows pictures or links to be posted until you pass a post count threshold.
 
Z06_Mir said:
I got a steering bungee from a scrap yard because Cessna wanted $7000 and 3 or more months for one. I'd bet you can find an actuator for 3000 or less if you look.
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These things bust frequently, much more often than a steering bungee, and they're probably one of the first things gone off a wreck. Besides, there are two versions of it, the newer one being stronger, and most airplanes will have the old, weaker one.

Breaking through the bolt hole implies, to me at least, that the bolts might have been loose. Or maybe the powerpack switch cutoff pressure is set way too high. Should blip off by 1750 psi or so.

Dan
 
I'd think cycles and usage are much more important than hours insofar as measuring wear on the retrac system is concerned. Has the plane been used as a retrac trainer?

smisek said:
So. I dont or cant post pics, but look at my profile pic. That is the problem I found. A completely cracked actuator through both sides of the bolt hole. Guess that was the explosion/bang sound I heard in cruise flight while the gear was up.

Found out Cessna has had issues with these since 2001 or early on all 172/182/210 RGs since that is the date of the original SEB, then revised in 2007. Amazingly it looks like Cessna has done nothing to improve the part... just check it for cracks...and if its broke buy the same dang one again. That's right, they will just sell you another one with no improvement from know defects for a mere $9000 plus the standard one year warranty, which for most of us might be a 100-200 hrs in a year? Oh...and if you do look for cracks referenced in their service bulletin, it makes no mention of looking for cracks at the bolt holes, or other places, only near the piston shaft opening.

Funny thing both of the actuators on this plane (4300TT) were replaced approx 1000 hrs ago. So there's the life expectancy. Two of these every 1000 hrs is just about the cost of a new engine, what a deal.

Thank you Cessna. Waiting for them to reply after sending photos.....yeah right I'm just a one plane owner...
Click to expand...
 
It comes to mind that another factor will break these things in a manner that the OP has shown. The leg is pivoted between two bearings, with the actuator mounted inboard of the inboard bearing. If that bearing is shot, laning and gear weight loads can put force on the actuator cover plate and shove up or down on the casting, or the pinion gear will contact the bottom inside of the housing (on landing and taxi) or the gear leg weight (in flight) puts upward force on the rack and housing. The actuator is supposed to do nothing more than rotate the pinion. If this actuator casting is the new one and broke after only 1000 hours, and a new one costs $8K, I'd be looking to see why it failed and why it didn't fail at the usual weak spot.

These other loads also crack the leg at the root of the shoulder between the gear spline and bearing journal. Some NDI needed there, maybe.

Dan
 
smisek said:
Anyone have input on why gear will not fully retract on a 1980 172 RG. Nose gear stows, right side stows, BUT the left side hangs down about 8-12 inches. Left side locks down properly, but even with slight help pushing up into wheel compartment does not go. No noises, no hard landings.

Just started. Was working fine until last cycle. 1000 hrs since left actuator was replaced, ADs done on checking gear in 2001.

:mad2:
Actuator, gear mechanism, both?

And I thought the radio was an important issue...

thank you.
Click to expand...
Check the fluid reservoir?
 
Thanks for all the replies.

Dan Thomas: I will check the bearings! I did not see any movement at the pivot points when putting force on the legs at different areas the other day, but will recheck that with someone else moving the landing gear. Plane did do some training, but was on a 135 ticket for quite a bit of its time, was inspected for cracks, and both actuators were replaced within last 1000hrs, 2004 & 2008. No mention of the bearings though, I think that might be an inexpensive just do it item.

Funny you mention two types the 9882015-2 or -4. The older one is still looking ok and we checked it for cracks. The "Newer one" -4 was the one that broke. Cessna techs were not able to tell us that Cessna made them stronger. In fact they said they had no idea there was any difference in the two.

This is a great sight. I've learned way more here, in a reasonable time frame, and heard nothing from Cessna. I did find the actuator at a couple of places and ordered one, will see what shape its in when it gets here. But hay for Cessna's unrealistic price I guess I can buy 2 or 3 from other sources and just keep installing them.

Thank you all.
 
So much for the avionics upgrade this year. Haha...
 
I hope you got a better price on the used units. Wow, that's a painful repair. I hope that keeps you flying for a long time before something else comes up.
 
Flown in formation with a 172RG a few times,


The RG was just a couple of knots slower than my 182, with the gear down...
 
Skylane81E said:
Flown in formation with a 172RG a few times,


The RG was just a couple of knots slower than my 182, with the gear down...
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Burning about half the fuel. Lets figure price of gas at $5 and a 5gph differential that's $25 an hour. Over a typical hundred hour year that's $2500. Figure 10 years of ownership that's $25,000. That's a lot of maintenance money you can dedicate to the gear.
 
Skylane81E said:
Flown in formation with a 172RG a few times,


The RG was just a couple of knots slower than my 182, with the gear down...
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For my money, it would be the R182, better known as the 182RG. Cessna really got the handling qualities right with that airplane. It doesn't fly like the FG version. What other airplane in that class has a Vso of 37 knots? What other airplane does a steep turn with almost no back pressure on the yoke? What older FG 182 has a TBO 2000 hours, or a Lycoming that doesn't need top-end work halfway to TBO? I always enjoyed the R182 when I flew it and maintained it. The biggest pain was jacking it so high to swing the gear.

Dan
 
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