HP-14 Landing Gear Gas Spring Retrofit
It became evident in the restoration of HP-14 N990 that the gear retraction system needed work. The gear was difficult to retract. As the gear retracted the springs lost tension. This caused the majority of the weight of the wheel to be supported by the retraction crank. As a result the bolt holes associate with the wheel yoke and crank connections became enlarged. In the extended position the springs acted counter to the over-center instead of reinforcing it.
While viewing the drawings of the HP-18 I saw the double spring/pulley system. I liked the way the system reinforced the overcenter lock. I ordered a crank, pulley, springs, etc. from Bob Kuykendall (http://www.hpaircraft.com). When Bob announced the HP-18 gas spring retrofit kit, I placed my order.
The HP-18 gear retraction lever is located on the left side of the cockpit. (The side stick is on the right side.) All previous models have the gear lever on the right side. The side on which it is installed has no effect on the installation. The only reason I mentioned it is to clarify the drawing.
18-585 spring bellcrank is 4 1/2 inches long. The distance from the retraction axle center mark to the gas spring attachment bolt is 3 3/4 inches. With the gas spring completely compresses it was just a little to long to mount on the axle support bolt described in the picture above; however, the forward top bolt allowed adequate spacing. The completed installation is pictured below.
(I am sure that many of you will notice that the turnbuckel is missing the required safety wire. The safety wire will be added prior to N990 being flown.)
This is a good system and the modification is highly recommended.