Submitted by FlyBoyMax (Max Givan) on Sun, 05/01/2022 - 15:21
Forums:
Having new and frustrating issue with my IV-P. In flight, air pressure inhibits nose gear retraction. Testing in shop, on jacks, nose gear gear operates normally until place light/moderate pressure aft on nose wheel to simulate air pressure. This inhibits nose gear retraction. A Lancair shop has been working issue for 2 months with no resolution and seemingly no plan to close on problem? Has anyone else had this issue and if so, how was it resolved?
My 2 cents,I would see if
Submitted by Erik S. on
My 2 cents,I would see if hydraulic pressure is on both sides of the cylinder. Check pressure itself. Or the piston seal is toast and leaking past. I do not know the leverage set up but is the over-center link to far over? Is the Pneumatic piston rod binding? All bushing tight but free?
Max
Submitted by rpastusek on
Max
As you are a long-time member/ Lancair owner, how long has this been a problem??
As the nose gear has to overcome the force of the gas spring used for emergency extension—which also holds it in the over-center position, low hyd pressure or an internal leak in the nose gear hyd cylinder could cause this.
Did you replace the gas strut with a higher-force unit? A 100 # force strut is specified-and should be tested at least annually.
Does your hydraulic pump continue to run, or run intermittently, without the mains or nose gear moving? This would indicate an internal hyd leak.
Have you installed the nose gear scissors link mod (SB 077-0518)? Do the upper and lower scissor links (drag links) pivot freely when the lower links are disconnected from the nose strut? It’s possible to introduce friction here if not properly installed.
I’ve spent some time on these issues recently and would be pleased to talk to you or your mechanic on this.
Bob Pastusek
757-286-4802
Hi Bob
Submitted by FlyBoyMax on
Hi Bob
Thanks for your input, Erik too. This is a new problem that presented in a return to service flight after spending quite a long time in the shop during which they did Condition Inspection, some avionics upgrades, gear door mods and some hydraulic work. I believe nose gear has had the scissors link mod but not sure? I have sent your and Erik's comments to the shop as I don't have answers to some of your questions and requested they call to discuss with you but not sure will happen. They, like most shops are overbooked and understaffed but I have requested they start by doing pressure checks, flush and bleed hyd system and if that is unsuccesful, rebuild/replace hyd cylinder. Your response does provide some new things to consider and test. Thanks and this is great example of the value LOBO provides to owners of these wonderful aircraft
Hello Max
Submitted by Laurie on
Hello Max
I have seen this problem on another aircraft after the drag long S/B. The link was going too far over centre and would not allow the nose gear to retract in some occasions.