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Subject: MDH 369 M/R P/C Bearing wear
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peri helixUser is Offline
JH Newbie
JH Newbie
Posts:4

09/21/2010 9:05 AM  
Hello, Anyone out there having trouble with the upper P/C link bearing damaging the clevis on the M/R grip. We have had several incidents on rotor hubs with 200 to 500 hours since overhaul. What I have discovered is that the bolt hole is drilled at a slight angle allowing only a small arc of contact on each side of the bearing within the clevis. If tightened normally it will be loose within a few hundred hours and start gouging out the clevis. Best part is that MD Helicopters is unaware of the problem no matter how many times we bring it to their attention. Is my company the only one having these problems? Lets hear it.
Hans kUser is Offline
JH Newbie
JH Newbie
Posts:3

09/22/2010 10:34 AM  

Yes we run 3 530 FFs , 1 500D . They eat the PC links . Centering rodends with the collective in mid position helps . The rubber washers can be cut easily . Also the swashplate ears get grooved . Once a company made a u-shaped stainless clip washer . This was a wear pad for the rod ends ,protecting the interior Pitch horn & swash sides .

I think boeing makes a boot covered rodend for the little bird . Not available to MD folks .



peri helixUser is Offline
JH Newbie
JH Newbie
Posts:4

09/22/2010 11:17 AM  
Hello Hans K,

Perhaps I misled you. The problem we are having is not the P/C link bearing cutting into the clevis (although that happens and it is a training problem). No the problem we are having is the holes in the clevis are not drilled straight, and when the bearing is installed and the bolt installed only a small area of bearing that contacts the clevis on both sides actually is in contact. About 30 to 45 degrees of arc is all the contact area on each side of the bearing where it touches the inside of the clevis. When it is tightened, with this small area, it is not long before it gets loose. It took a few incidents to see this and it was blamed on the mechanics not tightening the bolts properly, having done this for over thirty years I bristled at that one. I have brought it to MDH attention but they say they have not seen it before. I have also heard of an operator that recently (within a few weeks) recieved a hub from MDH and they found the misdrilled condition before they installed it. I do not know as yet what MDH did for them.

I am trying to find other operators that have seen this same condition so we might shove it up MDH's backside, so they will get off of it and do something about it.
Hans kUser is Offline
JH Newbie
JH Newbie
Posts:3

09/23/2010 9:55 PM  

I see , the sliding bushing should still hold the rod end ball . I dont think we have that issue here . I have seen plenty of mis-drilled swashplate stars . MD doesn't care if you bitch , they just raise parts prices . You need to find the vendor that built the head , send photos , measure angles .
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Forums > JH Alternate Forum > Helicopter Mechanics Forum > MDH 369 M/R P/C Bearing wear



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