Engine Mount - 800-Hour Inspection

[wlfpckrs]

I was just notified by our mechanic that we have a bent engine mount on our 2006 CTsw, and that it wasn't this way during our last 100-hour inspection. I was told that this is most likely due to a very hard landing, but neither of us co-owners remembers such a landing or owns up to it. Further inspection will determine whether there is any damage to the firewall. Are you in agreement that such a condition is most likely due to a single event - or the result of a series of imperfect landings over time? In the early days, we new pilots bounced it around pretty good, but that was a few years ago. Anyone experience a repair like this? Repair time and cost? File against insurance or pay out-of-pocket?

[N89WD]

I believe it would be a signgle event. Multiple bad landings would do other damage..ie, gear damage, etc.

[Roger Lee]

Hi Wlfpckers,

 

This is kind of a hard question. It could have been a series of landings or just one. If it was bent last inspection you would think the mechanic would have caught it. So if it really wasn't there before, then evidence would point more towards a single event. The repair could cost anywhere from $2500-$12K. The high number depends if you have more than just one mount bent and the labor to remove the engine and re-install it. This price may include a firewall fix too. I know of one in Tulsa that cost $15K. I think I would use my insurance and don't look back. Depending on parts it could be 2 weeks to 8 weeks.

[Mac Bowden]

Wlfpckrs, I would tend to think that the damage must be a single event. Most of my flying ends up in small agricultural fields of about 300 yards and while most of the landings are satisfory with the occassional 'greaser' I have been known to make e few 'arrivals'.Even recently I managed to give my noseleg a goog side swipe trying to slalom off excess speed and yet the engine mount took it with no ill effects. What and where is the exact damage to your engine mount?

Have a look at this photo of a recent fly-in to Ballina and you'll see the type of strip we use. This one is about 275 yards long with a rough bit in the middle where the hedge was. The CT was made for it! I'm not taking any credit for landing regularly into these strips but the point I'm making is that cumulative rough strips don't seem to bother the CT.

Mac

[wlfpckrs]

Our mechanic is getting into this inspection and mentioned that the rubber is cracked on the lord mounts on the firewall. Could that contribute significantly to the prop spinner sitting lower than normal?

[Roger Lee]

Yes it could. The outer one is the one that usually crushes way down because of deterioration. The inner one is usually ok. The engine ring mount bolts can cause or contribute, too. These are actually from a Fiat car. There are 16 of these in 4 locations. Cost is about $180 from FD. The engine has to come off to replace all these. There could be 2-3 things that could all contribute to engine sag.

[Mac Bowden]

When I compare my engine mount with other aircraft (C42,Skyranger,Xair etc)I've noticed that the CT is absolutely rock solid with virtuallly no movement when giving the prop a good pull.I don't have another CT in the area to compare with but feel that I'm getting a slight vibration coming through the rubber mounting system. What's your observation on the 'solidity' of the mounts? I'm aware that each mount location has it's own length of inner sleeve with matching bolts but sometimes wonder if the rubber hardens with age and that this could be the problem.

Mac

[Roger Lee]

Hi Mac,

 

Vibration can be caused by a number of things, but these are the usual causes.

prop blades not exactly the same pitch, prop not balanced, carbs out of balance, any of the engine mounts loose.

[Mac Bowden]

Hi Roger,

Checked all the usual suspects. The prop pitch is digitally within 0.1 degrees of each other the engine mounts are SOLID and am paranoid about balancing carbs (ex BMW rider)so are checked regularly. I notice a slight harshness at 2100 rpm and also again at 42000 rpm, which seems to be a harmonic doubling of the frequency. Now tell me, my Warpdrive came straight out of the box, fitted and was never checked for balance since last year ..... Problem? Is it customary to check them?

Mac

[Roger Lee]

Hi Mac,

 

Any new prop setup should be checked. The rpm's you list as suspect usually tells me to check the carbs. If it has some vibration at 4200 rpm then seems to go away at 5000 or more then it could still be a carb, but if you are sure the carbs are good then time to do a prop balance. If you have added a new prop then at least do a static balance with the entire hub assembly and not just the prop.

[wlfpckrs]

Pulling the engine to make this repair, would it make sense to go ahead and install the firewall insulation/blanket? I assume that, if we were ever planning to do it, now would be the best time. Having said that, I understand that it is optional, not mandatory. Any thoughts from any of you CT owners about the firewall insulation? How much would my part of the cost amount to? I'm not looking to spend money unnecessarily, but if it's a good idea and money well spent, I'll consider it.

[Ed Cesnalis]

Pulling the engine to make this repair, would it make sense to go ahead and install the firewall insulation/blanket? I assume that, if we were ever planning to do it, now would be the best time. Having said that, I understand that it is optional, not mandatory. Any thoughts from any of you CT owners about the firewall insulation? How much would my part of the cost amount to? I'm not looking to spend money unnecessarily, but if it's a good idea and money well spent, I'll consider it.

 

 

I'm sure someone will correct me if I'm wrong but.... Flight design pays a portion of the firewall blanket costs and much of the costs are associated with removing and replacing the engine. Perhaps it won't cost you anything since the engine removal is being done for another reason?

 

 

[Roger Lee]

Hi Wlfpckrs,

 

The blanket is voluntary only for now. There were approximately 110 CT's to do. Now there are only about 30 left. It will be mandatory before long. You all might as well get it done, sooner or later it will be required to get the last few done. This needs to be done to meet the ASTM standards. So the total cost is $1450 and FD pays $1000 of that so you are responsible for the $450. I highly, highly recommend to anyone doing the blanket that they replace the rubber engine isolators at that time because you have to pull the engine to replace them so why pay to pull the engine twice. The rubber isolators cost is approximately $180, there are 16 of them double stacked. If you need the isolators done might as well get the firewall blanket done. You are looking at a 2-3 day job to do the blanket. You really need to have some one do it that has done them before.

[wlfpckrs]

Looking forward to picking up N293CT in the next day or two. We did have a bent engine mount, but there was no firewall damage. Our mechanic spoke with Flight Design and was told that this wouldn't necessarily have been a one-event cause. Since we bought the plane, we've had three new pilots flying it, so there has been no shortage of hard landings, especially in the earlier stages of our training and flying.

 

Our partnership has worked well, but one of the drawbacks is that none of us can remember (or owns up to) doing anything to cause this damage since our last 100-hour inspection. Could this have been missed at the last and previous 100-hour inspections? Maybe.

 

We decided to go ahead and have the firewall blanket installed.