Loss of the aircraft during most overspeed situations is pilot error. While The overspeed may not be pilot error, failure to contain the overspeed certainly can be. In any event, one can only make the best of a situation that hopefully he does not create.
I recall a C-119 crash some time ago, which occured on a training flight. An overspeed occured, and the crew fought to controll it, while losing altitude. After 1/2 hour of struggling with the airplane, they crashed. The scenario involved in this case an engine that was developing good power, but had a prop overspeed.
Power was pulled, airspeed lost, altitude lost, and the RPM brought under control. As the aircraft slowed and became hairy, power was added, altitude and airspeed gained (or maintained), and a cycle was formed.
What the crew failed to grasp was that the RPM of the propeller, whenever not under positive torque, was dependent on airspeed. Had they slowed the aircraft and then used available power on the engine, they could have returned and landed normally...instead of dying.
If the engine isn't driving the prop, then the slipstream is. Reducing the relative wind that's driving the prop will reduce the prop velocity. This seems somewhat counterintuitive, as it brings the airplane to a state of reduced lift and potential controllability, however, it's what must happen. (Much like pulling aft and pulling power off during a tailplane stall in ice).
In the event that the engine can be controlled by reducing to a very slow airspeed, then very often power can be added and used. If it can't be, then the engine should be shut down, feather or not.
The ham standard prop on the brasillia and other modern aircraft is nothing like the hydromatics found on the P-61, and virtually every other aircraft of it's era. However, the principle remains the same. Ham standard props are well designed, tough, and reliable. I've rested my life on them, earned a living from them, and have handled them in all states from flawless function to destroyed. I've worked on them, overhauled them, and think the world of them. Don't blame the prop...it's nothing more than a mechanical device. The key is what is done with it when something does go wrong.
In the case of 529, it would appear the crew did it right. Unfortunately, it's very possible to do everything right...and still lose.
I recall a C-119 crash some time ago, which occured on a training flight. An overspeed occured, and the crew fought to controll it, while losing altitude. After 1/2 hour of struggling with the airplane, they crashed. The scenario involved in this case an engine that was developing good power, but had a prop overspeed.
Power was pulled, airspeed lost, altitude lost, and the RPM brought under control. As the aircraft slowed and became hairy, power was added, altitude and airspeed gained (or maintained), and a cycle was formed.
What the crew failed to grasp was that the RPM of the propeller, whenever not under positive torque, was dependent on airspeed. Had they slowed the aircraft and then used available power on the engine, they could have returned and landed normally...instead of dying.
If the engine isn't driving the prop, then the slipstream is. Reducing the relative wind that's driving the prop will reduce the prop velocity. This seems somewhat counterintuitive, as it brings the airplane to a state of reduced lift and potential controllability, however, it's what must happen. (Much like pulling aft and pulling power off during a tailplane stall in ice).
In the event that the engine can be controlled by reducing to a very slow airspeed, then very often power can be added and used. If it can't be, then the engine should be shut down, feather or not.
The ham standard prop on the brasillia and other modern aircraft is nothing like the hydromatics found on the P-61, and virtually every other aircraft of it's era. However, the principle remains the same. Ham standard props are well designed, tough, and reliable. I've rested my life on them, earned a living from them, and have handled them in all states from flawless function to destroyed. I've worked on them, overhauled them, and think the world of them. Don't blame the prop...it's nothing more than a mechanical device. The key is what is done with it when something does go wrong.
In the case of 529, it would appear the crew did it right. Unfortunately, it's very possible to do everything right...and still lose.
