iflyforpie wrote: ↑Tue Nov 03, 2020 9:16 am
trey kule wrote: ↑Mon Nov 02, 2020 3:58 pm
We are getting a bit off topic here, but yes to the cowlflaps. I don’t have the numbers for a 337, but IIRC, in the Navajo you could get about 50 extra feet of climb per minute with them closed. Both sides with an engine failure.
The problem with the 337 cowl flaps is they don’t have limit switches, and rely on the professionalism of the pilot. Dozens of burned out cowl flap motors from pilots who forgot. The same issue with the standby flaps in Caravans.
For the life of me I don’t understand the OEM thinking on these things.
You don’t understand the system. Neither did the pilot who taught me how to fly it and told me to leave the knob half a knob from full closed. Amazingly, neither did all of his previous AMEs who went through the cowl flap system and weren’t able to get it to work properly. And yes if you went to limits you’d pop the circuit breaker or shear the roll pin or burn out the motor.
So then I opened the Service Manual.. and found out that the cowl flaps are pretty much identical to a Cessna flap system. There are limit switches and about four pages of literature and diagrams for how to rig it. And like rigging anything; there are no shortcuts. You have to take it all apart and start at the very beginning. It took me hours but in the end, I had cowl flaps that could be abused by the most ham-fisted pilots and work perfectly normally.
So I stand by my opinion of the 337. The extra engine just means you are twice as likely to have an engine failure. You are OVER twice as likely to have an engine failure due to the possibilities of fuel mismanagement in an environment where you are distracted by constantly dodging obstacles, looking for fires/wildlife/etc, on trips that can last 7 hours. And due to the high altitudes, remote areas, and that the rear engine always runs hot.. the possibility of making an airport with that engine still running is not guaranteed. Then you have to deal with the other liabilities like higher turn radius, higher stall speed etc which makes forced approach in extreme terrain less survivable.
We've both flown the same type in the Monashee and the Selkirks on fire patrols and bug mapping. Generally, yes, the extra engine means you are twice as likely to have an engine failure. I don't think anybody is surprised by the math of that. What that means in a side by side is that while you may have quite a bit of time to pick where you are going to land, including at an airport, you do have the requirement to always maintain control and that is more difficult than in a single,
or a 337. In a side by side, the running engine can, and has, killed many people. That doesn't happen in a 337. There is no VMC roll.
I forget which one it is, but there is still sort of a "critical" engine on a 337. Not related to p factor on the running, but its a bit worse to lose one than the other purely in terms of performance. Okay, I researched it, and on pre 1973, you got 50 fpm less with the rear failed than with front stopped. After that, not much difference.
I know some talk about cooling difficulties on the back engine, but I don't recall it running at a significantly higher temperature. Conversely, it does seem that the rear needs a top sooner than the front.
If you are in the BC mountains, and you're in a situation in a 337 where anything whatever depends on the difference in turn radius, you're probably gone already for something you may have done minutes before when you allowed an airplane to descend into a situation where turn radius was all that was going to save you. I suspect IFly is talking about the specialized work of fire spotting for the BC Forest Service and what they called "mapping" the fire, where it was presumed that a pilot's licence included some special ability in assessing fuels and risk and I forget what else. I do remember that it was a task that in many situations could not be done safely. So I didn't do that. I told them there was a fire, it was spreading, crowning, whatever, and to send tankers if that was obvious. They were going to send a chopper anyway. My job is not to be down doing steep turns in gulches and canyons trying to identify the species of shrubbery that was burning, or whether the squirrels were nervous. You can do everything they require, which is providing information, orbiting at 500 feet above the fire and never worrying about turn radius.
I'm not sure it was entirely the gear doors that complicated the engine out procedure on takeoff. I remember that part of the drag came from the gear transiting profile in which the wheel was broadside to the slipstream for a short time.
We are off topic about the Smithers crash. While I remain baffled about how some see a ditching on a shoreline as such a Doomsday scenario that they would prefer to fly into trees, in this particular case, I don't fault the pilot at all. He really didn't have any other choice. That he was aware of. When the engine lost power, he was within easy sight and gliding distance of the Silver Hilton strip. He didn't go there, it apparently wasn't in the GPS database, and that choice, although there, wasn't available to him. It does seem that the course he took up was mistakenly believed to be for the same strip he could see outside his window.
This crash was caused by issues with the carb heat capabilities of the unusual STC that was in the thing, and we can learn from that and some of the lads here are very knowledgeable on that and informing us. Not sure what can be learned from flying away from safety.
Good judgment comes from experience. Experience often comes from bad judgment.
