[JAG]

Unfortunately I only have schematics and a manual up to S/N 01462 so I can't provide any direction on the hydraulic pressure/power pack potential problems. However given my knowledge on the earlier models, the rigging is important to have sorted first. It sounds like the overcenter has not been rigged properly with regards to the downlock and associated linkage. The downlock should not overcenter until the gear contacts the overcenter release bolt on the downlock.

Potential causes in the rigging of your symptoms:

1. Is the downlock clevis shimmed properly? If it is over shimmed, then with pressure acting on the downlock during the gear extend sequence, it may move the down lock beyond overcenter once pressure is supplied.

3. is the Overcenter Stop bolt rigged correctly? If it is too far out, the downlock will overcenter before gear is up in the support.

2. Overcenter-arm button is too far out, allowing early release of the downlock. On the earlier models, during the gear extend sequence, the pressure is building up in the downlock during the extension. The overcente-arm with spring is also holding the downlock from overcenter (along with the proper rigging above). As the spring-gear comes up into the support, it will contact the overcenter button and now all the downlock needs is a little nudge from the gear on the overcenter release bolt and the downlock kicks over.

Again - by the description you provide, it sounds like the overcenter is not happening with the downlock.
Jeff