NASA Aviation Safety Report

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GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

NASA Aviation Safety Report

Post by GAHorn »

I rec'd the NASA Aviation Safety Report in my email and read it. This publication often presents a real-life scenario which was self-reported and asks the reader to thing about "What would YOU (the reader) have done?

Here's one similar to one that I've actually had happen to myself.

Twin Throttle Technique
Duchess Instructor’s Report
Twin Throttle Technique
Duchess Instructor’s Report
■ My student and I were practicing a simulated single engine approach.… We crossed the IAF at 2,000 feet, and then I reduced the left throttle to start the simulation. My student started to practice the emergency procedure: maintain directional control and altitude, full mixture, full props, full power (right throttle), flaps up, gear up, auxiliary pumps on, identify and verify “dead foot dead engine.” He identified the dead engine [as] the left one, so we [set] zero thrust and continued the maneuver. At this time everything was all right. Then we crossed the FAF. My student tried to decrease the manifold pressure of the good engine (right one)…to descend.… Then I realized that the manifold pressure in the right [engine] did not decrease. I took the controls and I canceled the maneuver, putting back the left prop and throttle. When I tried to decrease both throttles, I saw that manifold pressure of the right engine did not decrease.
What would YOU have done?

The Reporter's Action
■ I was talking with Tower at this time.… They asked me if I wanted to take Runway 32 or circle for Runway 28. The conditions were VFR, so I canceled the approach and started to align the plane for landing on Runway 28.… My right engine was [operating] with full power due to the throttle level [being] unable to control.… I [flew] with the left…engine at idle…to maintain a safe and stable approach.

On short final when I was sure about my landing and everything was safe with usable runway, I killed both mixtures at the same time and feathered [both] of the engines.… I landed and vacated the runway in the protected area and shutdown the plane.

======
My opinion: I'm sorry the instructor took the action he did, but glad it turned out OK for him. It could have been much worse as you might imagine.
It's unlikely that adding drag devices such as gear and flaps wouldn't have brought the airplane back to a normal mode of operation by idling the good engine
Even if a Duchess had excess power in the malfunctioning engine (unlikely considering it's an underpowered airplane on it's Best day...)… a better solution in my opinion would have been to restore the simulated engine-out to normal operations, then shut down the malfunctioning engine and demonstrated to the student the proper method of landing a multi-engine airplane on one engine. That would have been a much safer method of dealing with the problem as well as turning the event into a valuable lesson.

In my own former experience, I was making a normal visual approach to Kerrville airport in my passenger's-owned Baron and the right throttle would not reduce from cruise power for the landing. (The right throttle cable had seized from old-age/lack of lubrication.)
My solution was to reduce the power on the correctly-operating left engine to manage the approach... to the point of complete idle power....and continued the landing, which was only slightly faster than usual. On rollout, I pulled the mixture of the right engine and used the left engine to vacate the runway, then called for a tug and shut down on the taxiway.

In the NASA report, I feel it was probably unwise to feather both props on dead engines while still in-flight/before landing. I feel this way because of another incident I experienced while flying a Beech 99 with a "playful" training-captain in the right seat. While in the "flare" he feathered both props. (The PT6 engines were idling but quickly restoring power was impossible.) The sudden reduction of thrust coupled with the loss of ordinary prop-disc-drag caused a huge BALLOON and there we were 15' high with runway being eaten-up at a rate much faster than normal! The airplane refused to slow down! 8O
Fortunately it turned out OK but I had to PLANT the airplane at higher-than-normal speed and judiciously use braking to avoid skidding tires while remaining on the (now much-shorter) remaining runway..... AND, since the props were feathered, REVERSE thrust was also denied us, something normally expected on every landing.
My training captain was as wide-eyed as myself due to his foolishness. 8O

In the mid-1980's I witnessed the local commuter airline operating the same model airplane, landing in front of our corporate hangar on Rwy 17 at AUS Mueller. While the flare was in-progress I heard both props suddenly go in to "feather". That crew blew all four tires, ruining all four wheels to stop in the remaining runway.

Althougth these particular scenarios are unlikely to occur in our Cessna 170 aircraft.... I wanted to post this thread becasue I want to remind everyone that practicing something never-before-experienced in a "last-minute-idea".... is probably a very BAD idea as well as an example of really poor judgment. It's a good idea to avoid such silliness.

Hope this is taken in the right frame of mind. Good judgment is the hallmark of good piloting and playful, last-minute ideas are generally not part of that.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
G280driver
Posts: 48
Joined: Thu Oct 27, 2016 10:12 pm

Re: NASA Aviation Safety Report

Post by G280driver »

George I agree with you that the instructor gave a terrible example of overall how to handle the situation. The worst is that typically reteaching to proper instruction is very difficult as humans tend to remember what their first taught and not so much the relearning.
About 20 years ago flying our 310Q from San Antonio to College Station I had a somewhat simular event. When i reduced power to start my descent into CLL the right side didn’t reduce. Confirmed this and simply put left side to idle, Rt side prop full forward and opened cowl flaps. Entered the pattern as a normal approach. When I knew I had the runway made I closed Rt cowl flaps, pulled the mixture and feathered the prop. Added power as needed on the left and made an uneventful landing.
A little further back immediately after an engine change on a 182 repositioning to home base I had a sudden rpm drop of 300-400 rpm. I was loosing about 50 to 100 fpm. I knew I wasnt going to make it to my destination so I diverted to an airport just a few miles off my course. Not knowing what was wrong I was unwilling to change anything as the engine was making power, just not enough to maintain altitude. I lined up on final and at short final attempted to reduce power, nothing happened. I had a decision to make. So I pulled the mixture enough to reduce the power and then added fuel to keep it running and descend to land. It was slightly challenging keeping the engine running but shut down enough to reduce power. I side stepped and landed on the taxiway and kept enough momentum to roll up to the maintenence hanger. As it turned out the throttle cable came unbolted from the carb linkage. I found the castlated nut inside the cowling so Im assuming the cotter pin was never installed. 30 minutes and I was flying again.
Since flying Jets Ive had to do two inflight shutdowns because thats what the checklist said. Also had a jug seperate from the crankcase while on an ILS in the 182, but those stories are for another day and are off topic.

I had a great instructor and an uncle who have mentored me along the way. I owe everything I am as a pilot to those two guys, and they know it cause I tell them both. They beat into me
Fuel on the ground is useless
Runway behind you is useless
Altitude above you is useless
Snap decisions can kill you
Skud running is plain stupid
And lastly Train like you fly and fly like you train
1953 170B “Deuce” 25582
1951 170A “Blue Lightening” Sold 20021
hilltop170
Posts: 3481
Joined: Sat May 06, 2006 6:05 pm

Re: NASA Aviation Safety Report

Post by hilltop170 »

I was flying a C182 from Texas to Alaska and was between Prince George, BC and Watson Lake, Yukon in “The Trench” at 4500’msl in cruise. I decided to climb so eased the throttle in but nothing happened. I eased the throttle out and it decresed 1/2”Hg then tried to increase and again nothing happened so I locked it down hard so it would not move on its own as I had about another hour to the next closest airport at Watson Lake.

I had plenty of time to think about what I was going to do and decided I would leave the throttle set where it was at about 23”Hg for approach and landing and would use the mixture to lean it out to control rpm. 23”Hg would barely allow a go-around if necessary but I did not intend to go around unless it was life or death.

Everything worked as planned and leaning the mixture, with the prop in full increase/high rpm acting like a fixed pitch prop, allowed control of rpm for a normal landing and taxi to the gas pump.

The plane had an annual inspection before departure from Texas and the IA told me he re-routed the throttle cable over the generator bracket since it had run under the bracket which he said was wrong. Re-routing the throttle cable caused it to kink where it crossed the generator bracket which stressed the outer housing until it broke about 16 hours later. Luckily the inner cable itself did not fail or all throttle control would have been lost. With the outer housing broken, advancing the throttle just caused the outer housing to separate apart and not increase the throttle while decreasing the throttle brought the broken outer housing together and actually decrease the throttle. It was a one-way street.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
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