I’m a hot weather wimp. People that know me know that I hate the heat. I don’t fly when the temperature is in the upper 80’s and certainly not while it is in the 90’s. However, there are rare occasions that I get to fly aircraft with air-conditioning and one day I got just that chance in an older model Baron. I was skeptical at first, but the Baron had a neat contraption in the back that made use of a picnic cooler and a big bag of ice that made the cabin relatively comfortable.
With temperatures in the upper 90’s, pre-flight was brutal,
but necessary. Once we hopped in the
aircraft and started the ice machine, things got comfortable quickly. We went through the Before Take-off checklist
and reviewed V-speeds, then started our takeoff roll.
Power application seemed normal, but takeoff roll took some time. While I was not exercising duties as a flight instructor on this flight, I couldn't help but do my usual routine and eventually locked my eyes on the airspeed indicator watching for lift-off speed. It seemed to take forever, but in reality, it was probably only a handful of seconds.
I will admit, my senses were a little piqued because just the day before, I was watching an online video of a Beechcraft Duke take off and pull right up into a barrel roll, with disastrous results. Was it an engine failure right at take off or something else? We will have to wait for the NTSB Probable Cause report on that one, but recent news has shown a rash of other incidents where multi-engine aircraft have met their demise shortly after takeoff. This got me thinking: If I did have an engine failure just after takeoff, while retracting the gear, what does single engine performance look like in this heat? Are we spring loaded to do what we need to do if something happens at this very critical moment on takeoff?
Running the numbers on many Barons 55s with students over the years, I concluded that in only the most extreme situations would there be a situation where you wouldn’t at least get about 200fpm in Midwest field elevations, if you immediately and correctly feather the dead engine’s propeller and fly the airplane precisely in zero side-slip, blue line flight. But is that true in this heat? It was quite warm that day and was curious what the performance characteristics looked like for that day.
Let’s take a look at the numbers for single-engine climb performance from a B55 Baron flight manual. The numbers for today are as follows:
Field elevation: 591
Temperature: 97F/ 36C
Weight: 4900 pounds (200
pounds below gross weight)
Looking at the graph (See figure), we start from the bottom with the temperature. Slide upward to intersect the line that shows our pressure altitude – close to field elevation most of the time. This combination of pressure altitude and temperature accounts for density altitude without actually giving you the density altitude number (We are essentially figuring out the density altitude component of our day on this portion of the graph.) From that point, make your way to the weight of the aircraft. Move upward toward the weight of the aircraft and then over to the right and you will find your resulting climb rate straight ahead at zero-sideslip blue-line with one engine inoperative and its propeller feathered.
Mind you, I am not flying with a high-performing test pilot,
nor is this aircraft brand new. The
engines are both near TBO, so we are not likely getting the same performance a
new engine may provide the test pilots that helped create these graphs in the
flight manual, so even conservative numbers need to be adjusted a bit more conservatively.
Was the result what you expected? A little lower than you thought? Does a figure like 350fpm give you confidence, or does it give you pause? In your airplane, do you know what a 350fpm climb looks like or feels like when you are making more than one mile a minute across the ground?
These are some questions that need to be considered in addition to reviewing your preparedness for an engine failure on takeoff. So, while we may get 350fpm climb on one engine, expect to lose some altitude as you go through the phases of disbelief, maintaining control of the aircraft and then feathering the engine. A half standard rate turn in a Baron on one engine reduces climb rate by about 400 feet per minute, so the moment you try to turn, the airplane begins to descend. In aircraft like the Baron where we are used to 1000fpm climbs, 350fpm is an eye opener.
Before every take off, I call out “think single” just to remind myself to be mentally prepared for what I need to do. It sounds simple, but I think it helps. Review your engine failure checklist. What are you going to do from memory? The usual flow goes something like this: Power up (mixtures, props, throttles forward), Clean up (gear and flaps up), Identify (dead foot, dead engine), Verify (retard throttle to confirm no change), Feather (the correct propeller). The only problem with this flow is that it is missing a critical component: Pitch. The very first thing that you should do is pitch down to the attitude that will give you blue line on one engine. That’s about three degrees nose up before you feather the prop, or essentially push the nose to the horizon. After feathering, the reduction in drag means you must pitch up to about seven degrees for blue line. At a high-density altitude, you will need to lower the nose a degree or two lower than these figures. You must know these attitudes for your aircraft and the conditions of the day, and understand that it is much different than pitch required for blue line with two engines running.
I encourage everyone flying a Baron or Travel Air to take some time to review the numbers for single engine performance and if possible, do some demonstrations on how it climbs on one engine so you can see what climb attitude looks like on one engine at blue line – both on instruments and visually. Grab your favorite MEI and run through some of these simulated scenarios. Flying with someone who really knows the single-engine performance of your Beech twin is a great reason to fly with a BPPP instructor if you’ve never done so before… or even if you have.
I hate the old saying about multi-engine aircraft where the operating engine takes you to the scene of the accident, but unfortunately it’s true if the pilot is not prepared as some of the latest multi-engine accidents have shown. It’s our job to stay sharp and well trained so that we can have a positive outcome in the unlikely event of an engine failure.
Next time you are out flying on a hot day, think of me. I will likely be on the ground in the FBO watching the planes, or in an air-conditioned aircraft – maybe with one of those picnic cooler contraptions in back! More importantly, think about the heats effect on aircraft performance, especially on one engine.