Home > VansAirForceForums

-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
w/a Donation

VAF on Twitter:

Old 02-19-2023, 12:27 PM
rcarsey's Avatar
rcarsey rcarsey is offline
Join Date: Jul 2012
Location: North Brunswick, NJ
Posts: 418
Unhappy Rv12iS gearbox chatter

I have about 390 hours on the engine now.. Within the past month, I've noticed a vibration in certain situations. Initially, I believed it was on unbalanced front tire which was rotating in the wind.. But after rebalancing it (only 1/4oz off), I am faced with a more expensive problem.

The vibration seems to happen when I throttle back, for instance, before I begin a descent. If I advance the throttle a bit again, the vibration seems to (immediately) go away. In stable air, at a fixed throttle setting, it does not seem to happen.

From what I've read, almost all gearboxes (especially with 100LL use) need servicing at the 600hr inspection. Ok, mine is a bit.. 30% earlier.

Assuming this is the actual problem, two questions:

1. Is the aircraft safe to operate? The vibrations aren't shaking the plane, but I can feel it in my feet. I don't want to continue operation if its going to cause damage to other parts . The last oil change 50 hours ago showed NO debris.

2. Is this a problem I want/can fix on my own? I don't mind spending some $ on specialized tools, especially if this will be happening again down the road. And if so, which gears/item #s will I want to buy before I start disassembling it (assuming I can still continue to fly it between now and the time I get parts).
Rob Carsey, Winfield Park, NJ
RV-12iS (N713) / Completed 12/2020 / 350hrs and counting
APRS Track or ADSBExchange Track

Last edited by rcarsey : 02-19-2023 at 01:27 PM.
Reply With Quote
Old 02-19-2023, 01:32 PM
Bob Y Bob Y is offline
Join Date: Jul 2017
Location: Piedmont, SC
Posts: 470

Probably a good question for the Rotax Owner forum, if you’re a member. You could ask Lockwood, but they’ll likely suggest pulling the gearbox and sending it to them, but probably worth asking anyway.
Bob Y - builder 12iS
N569TT first flight 2/9/2020
Reply With Quote
Old 02-19-2023, 03:15 PM
philcam's Avatar
philcam philcam is offline
Join Date: Aug 2005
Location: DFW, Texas
Posts: 219


I assume your prop is balanced?
Phil Campbell
Eagle's Nest Projects
VAF # 1043
Builder # 82699
DFW Metromess
Reply With Quote
Old 02-19-2023, 04:20 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,875

With 100LL.... perhaps check overload clutch per Rotax maintenance manual with fish-scale spring. Lead contamination is tough on the gearbox. Gears spin lead against walls of gear case and clutch plate friction surfaces get slippery.

I have early SN RV-12 and my 912ULS has >800TT operated on 93E10 with no gearbox problems. Some of the early gearboxes had improper heat-treat, but apparently I got a good one.

Also, I'm using Mobil1 Racing 4T Full Synthetic Motorcycle Oil 10W-40 exclusively....
Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H

Last edited by Piper J3 : 02-19-2023 at 04:27 PM.
Reply With Quote
Old 02-19-2023, 05:30 PM
Taltruda Taltruda is offline
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 1,504

Sounds like you use 100LL, isn’t the oil change interval more frequent than 50 hours? I thought it was like 25 with 100LL..
Las Vegas
RV-4 flying…
RV-8 empenage finished 10-2020

Wings Started.. 11-2020
Reply With Quote
Old 02-19-2023, 06:07 PM
henrysamson henrysamson is offline
Join Date: Jul 2022
Location: Austin, TX
Posts: 2

It used to be 25 hours but is now 50.

Reply With Quote
Old 02-19-2023, 06:17 PM
Dvalcik's Avatar
Dvalcik Dvalcik is offline
Join Date: Jul 2011
Location: Royersford, PA
Posts: 935
Default Gearbox

Rob, I would call Lockwood and talk to them. I had mine done at 600 hours even though there were some signs of wear we went ahead and replaced the needed parts.
Royersford, PA
Lifetime EAA member Chapter 1250
2023 VAF Supporter

RV12 #568 EAB
* Started 9/30/2011
* 1st flight 8/30/12
Reply With Quote
Old 02-19-2023, 06:39 PM
funflying funflying is offline
Join Date: Oct 2006
Location: arvada, co
Posts: 533

Great to see your post Dave. I haven’t noted any issues but am just over 600 hours and plan to send my gearbox for service. I’ve been told by a Rotax mechanic that following the maintenance schedule on my 912 it will operate great throughout the TBO period.
I wondered how some of the higher time RV12’s followed suggested maintenance schedules.
Patrick Claar
Arvada, CO BJC
RV12, #401, Flying 2013, N612PC
RV6, 1996-2010 sold
Reply With Quote
Old 02-19-2023, 10:03 PM
RFSchaller RFSchaller is offline
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,369

Mine has 1280 hrs. Almost all on no lead auto gas. No gearbox issues. Mine is an ELSA, and I did not pull the gearbox for the 600 hour check. My reasoning was that this check primarily looks at the overload clutch breakaway torque on the dogs, and that is a prop strike protection. I go with plan A: no prop strikes. I do the breakaway torque check at annual that basically checks the spring pack force. It has always been in spec since first flight in 2012.

I always appreciate respectful comments that might challenge my position.
Reply With Quote
Old 02-21-2023, 06:19 AM
mcems mcems is offline
Join Date: Apr 2008
Location: Salem SD
Posts: 175

I have 1200 hours on mine also using all no lead gas. I did not do the 600 hour rebuild. I also check the specs at annual time Its always within the numbers in the manual.

Brad Stiefvater
Salem SD
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -6. The time now is 05:43 AM.

The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.