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From: John Barrett <2thman1@gmail.com>
Subject: Re: [LML] Re: Gear Strut Compression Tool

Personally I would not rely on a free fall test to check the air strut.  Way=
 too much at stake if you're wrong.  I would think the nose gear could free f=
all perhaps without adequate air strut effectiveness.  Until someone tests t=
his with multiple air struts that have various strengths I would not trust t=
his.

I like Grayhawk' s and others' comment about undoing the scissor arm at the n=
ose strut either to test the air strut or to compress it for reinstall.  If t=
hat works for the strut it has the added bonus that you remove the scissor a=
ttach point, inspect, clean and lubricate it, which should also be done peri=
odically.  I'm thinking if this works I might alternate with strut removal o=
ne year and scissors attach point the next. Haven't tried it even though I c=
onsidered it, but I'm wondering if the hydraulic cylinder allows a enough mo=
vement of the scissor to effect a compression of the air strut.  Does it wor=
k without removing the hydraulic cylinder attachment?

On Bob's discussion of the emergency down pump system, I always thought the d=
esign of the reservoir is suspect.  It has a thru bolt that comes up through=
 the bottom of the tank with nothing but a rubber gasket to prevent leakage o=
f hydraulic fluid from the very lowest point of the tank.  It was a long tim=
e ago to recall the details, but I had someone weld the rod into the tank to=
 reduce the risk of losing all hydraulic fluid in the tank with resulting ge=
ar up landing.  That could mess up your whole day.


My .02.

John

Sent from my iPad


On Apr 7, 2013, at 7:20 PM, Robert R Pastusek <rpastusek@htii.com> wrote:

> Dennis wrote:
>=20
> I know this might not work in a Lancair IV, but in my Legacy, I do an alte=
rnate gear extension test in flight, using gravity and the gas shocks, to co=
nfirm that I get three down and locked.  If it works, I don't think there is=
 any need to remove the gas shock and test it.
>=20
>=20
> Dennis,
> As designed by Lancair, the IV/IV-P mains will "free fall" to a trail posi=
tion when the "up" pressure is removed from the gear retraction cylinder. Th=
ey will not fully extend and lock down because they have to move forward aga=
inst the airstream. Because of the design, there is no reasonable way to att=
ach a gas strut to assist this, although some folks have devised various alt=
ernative "automatic" extension systems. The Lancair solution was to mount an=
 emergency pump between the front seats to pump the mains down. Works well i=
n all situations except some broken/leaking hydraulic line emergency situati=
ons. The reservoir even has a pick up for the emergency pump that is lower i=
n the tank so there is some fluid left after the electric pump starts suckin=
g air.=20
>=20
> The IV/IV-P nose gear is extended by a gas strut just like the Legacy, and=
 should extend and lock down any time the "up" pressure is removed from the n=
ose gear retraction cylinder. Part of the recommended condition inspection i=
s a flight test to confirm that it will extend at or above 120 KIAS when the=
 hydraulic pressure is depleted--(and that you can also pump the mains down a=
nd locked). My nose gear will extend and lock down reliably at 140 KIAS so I=
 have not removed and tested it with a bathroom scale as recommended, but I'=
m thinking that this year is probably time to do so...
>=20
> My two cents...
>=20
> Bob=20
>=20
>=20
> --
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