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Hello!
I visited my Lancair yesterday at the airport to remove the canopy and header tank and inspect the damage to the nose hydraulic cylinder attach point. Here's what I have found so far:
1. The aft end of the phenolic hard point had totally failed. 2. The nose gear hydrualic cylinder DOES bottom-out on the UP side but about 1/4" travel on the DOWN side remains. My nose gear setup did not use any of the external cylinder stops.
3. The fiberglass OVER the phenolic block seems to be a bit FLIMSY and SOFT. Only a 2 or 3-bid lay-up to hold the phenolic in place. 4. I discovered a slight header tank leak and some areas of the failed area was stained with AVGAS (Now I know where the smell of AVGAS comes from whenever I forget to shutoff the transfer pumps). Question: Will this cause the fiberglass around the hard point to weaken?? Last night I checked the manual again. In Chapter 13, Gear & Gear Door Adjustments, the manual goes to great lengths in stressing the importance of UP-LIMIT-STOPS (High Pressure side of the gear cycle) but makes no reference at all (that I can find, at least) regarding any DOWN-LIMIT-STOPS. From this observation I have to conclude that the factory, at least initially, was not overly concerned about creating LOW-PRESSURE limit stops on any of the gear mechanism. It could well be acceptable NOT to create DOWN-LIMIT-STOPS if only the hard-point was of a beefier design. I am willing to bet that when I remove the bolts on the outbd side of my MAIN gear hydraulic cylinders will show that it does not bottom out either on the LOW-PRESSURE cycle... However, the hard point of the static side of these cyclinders are quite massive and probably not a problem (haven't heard of any failures in this area, right?).
Probable Course of Action:
1. Apply 6-bid over the entire nose gear mound, where a big hole now exists, extending to the sides and some overlap fore and aft.
2. Hysol a bigger sized phenolic hard point to the inital 6-bid layup.
3. Apply another 6-bid over the phenolic hard point, again extending to the sides and fore/aft areas of the outer tunnel.
4. Ensure that the hydraulic cylinder reaches it's stops, under pressure, either externally or internally.
Did I miss anything? Overkill? Comments??? I will call Lancair again to see what they have to say on this matter. Again, thanks guys for your input on this matter. The part about bottoming out the downside of the gear cycle makes a lot of sense... Rick Argente N360ZR
...grounded.. :-( [If you simply screw the rod end further onto the cylinder's piston rod you
will shorten the length of the down-stroke. Just let it reach that
point at the same time over-center link locks and everything should be
okay. It will pull the wheel a bit further into the well, but you should
have adequate clearance to do so. If not you'll have to go with an internal
stop in the cylinder. Your repair schedule with the additional
phenolic and BIDs sounds more than adequate... I'm sure the factory will
put their blessing on it. Sorry to hear that you have to go through this
entire activity, though... it would obviously be lots more fun to simply
fly off that 25 hours. <Marv> ]
LML homepage: http://www.olsusa.com/Users/Mkaye/maillist.html
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