Karmutzen wrote:Lots of single turbine otter operators around here, none seemed concerned. Tail inspection here is required on every 100hr. That component on that plane was looked at by maintenance on April 21, not that long ago.
Talked to a corporate Turbo Beaver pilot last week that had his trim control come apart on takeoff (runway, amphibs). Corrosion, with the result that it oscillated between full down and full up elevator trim. He figured out a power/control combination to keep it nose down, and had the front seat passenger help him hold the nose level. Once they had it sorted and stable he came around for a landing. Those get more frequent inspections now too.
Curious why if the elevator comes disconnected why it isn't flyable on trim. Happened in cruise and it turned into a lawn dart. I'll try have a look at one tomorrow and find out more.
Otter tailplane is a completely different design than a turbo beaver. Otter has a trimming stabilizer with a jackscrew attached below the leading edge and 2 hinge points below the trailing edge. It’s R/H elevator has a servotab where you would expect a trim tab and the L/H elevator has a “flap compensating tab” similarly located.
Turbo beaver, and recip beaver, has a jackscrew mounted below the stabilizer trailing edge which drives a bellcrank assembly and 2 trim rods which actuate 2 traditional style trim tabs.
If the jackscrew on a beaver becomes jammed you’re stuck with unfavorable trim forces, it can’t really come apart like the jackscrew in the accident otter did.
If the jackscrew on an otter suddenly loses its top then the stabilizer is free to violently bang between its two extremes of travel. At this point the pilot is, at best, faced with pitch control reversal but is most certainly totally fucked.