PA-32 Cherokee Six/Lance/Saratoga/6X
Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 45; Flight Crew Total 15000; Flight Crew Type 500
Troubleshooting; Training / Qualification; Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Human Factors; Weather
While flying a cross-country; I encountered strong mountain-wave action; making altitude difficult to hold. I asked for and received a 'block altitude'. The conditions were VMC all the way to the surface. The aircraft was on autopilot with altitude hold engaged. The autopilot called for 'trim up;' as the aircraft was descending I added power. I asked the other pilot to give it nose-up trim as he had done several times before. (The aircraft only has manual trim.) Suddenly; the aircraft nosed over. I immediately hit the autopilot disconnect button and pulled the circuit breaker. I noticed that the aircraft was very nose-heavy and I struggled to keep it from pitching down further. I called for more nose-up trim; but the problem got worse and I could barely slow the pitch-over even by pulling with both hands.During our descent; the controller queried us about our rapid descent. Given that I was extremely busy; I advised ATC. Finally; I told the other pilot to help me pull the nose up; whereupon the aircraft responded and I began adding nose-up trim and climbing back to altitude. We arrested the descent and leveled off and then I began the climb back to cruise altitude.I checked the aircraft for any control difficulties and determined that there were none; I advised ATC that I was climbing back to cruise altitude. Upon discussion with the other pilot; we determined that instead of adding nose-up trim; he was inadvertently adding nose-down. Because the autopilot had been engaged; we did not notice the wrong direction trim. We continued to our destination to get clear of the AIRMET for turbulence. Upon landing; an A&P inspected the aircraft and found no evidence of over-stressing the aircraft.
PA32-300 Pilot reported mountain wave activity and improper operation of trim resulted in loss of aircraft control.