In a message dated 2/28/2006 9:39:52 P.M. Central Standard Time,=20 goconnell@dodo.com.au writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Hi guys,=20 I do not own jacks for my aircraft and the method the shop has been using=20= for=20 jacking has been to place the jacks outboard of the main gear and use thic= k=20 foam padding to protect the wing. Is this an acceptable alternative or is=20= it=20 likely to cause structural damage. I have noticed some hairline cracks in=20= the=20 gelcoat on close inspection.

If your 320/360 was built according to the plans, there are phenolic ja= ck=20 pads placed at the intersection of the aft edge of the main spar and the inb= oard=20 edge of the cockpit closeout rib. This places the pad under the=20 glass continuation on the belly floor of the load transfer structu= re=20 that securely attaches the fuselage to the main spar. From the outside= ,=20 the general location of the central part of the jack pad is 1" to=20 1.5" inboard of the inboard gear door hinge and a bit (1" or less)= aft=20 of the forward edge (corner) of the door opening. This is a very stron= g=20 area and it is this location of a jack lift point that requires 120 to=20= 150=20 pounds applied to the tail (tail tie down ring) to lift the nose off the=20 ground. It is expected that the tail would also be supported for safet= y's=20 sake.

You don't say exactly where the shop is applying lift pressure. I= f=20 the lift is applied from about 1 inch inboard and 1 inch outboard of the=20 wing/stub-wing split and behind the main spar, the pressure is being applied= to=20 the stub wing rib and the inboard wing rib and these ribs extend to the oute= r=20 skin. While this is a strong area , any deformation could mean the=20 rib has been deformed - this is a structural no-no. If the=20 pressure was applied under the main spar - just outside the outboard door=20 opening, but not beyond the split, perhaps only the paint is damaged but sin= ce=20 this is forward of the designed lift point, I don't know whether weight is=20 required on the tail or the tail has to be supported (it should be supported= in=20 any case), If the pressure is outside the split it would have to be=20 forward of the main spar to be under the wing spar - this is not a very good= =20 balance point even if the wings are holding up the whole plane in flight.=20

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)