26 Oct 2017 - 2 dead after plane crash near Springbank Airport, west of Calgary

[pelmet]

The schools SOP was to use a reduced takeoff power setting of 35 inches. If you think that is a power setting that doesn't use any turbocharging, you're wrong. But, it is less than the POH takeoff power setting of 40 inches.

Why was there upwards of 1/3 less performance during this flight? I certainly do not know, but it stands to reason that this instructor was doing something very idiotic and had a record of simulating engine failures on takeoff before. Accident waiting to happen, especially with an unsuspecting student.

The way I read the TSB statement, there was 2/3 less performance on this flight(or 1/3 the performance). But like you said......"unsuspecting student" is a possibility. Which is why I said earlier....discuss with the instructor before the flight on what they plan to do and then monitor them with suspicion during the critical portions of the flight.

[iflyforpie]

Most light turbocharged engines have low compression pistons. Even if you’re boosting the engine, your BMEP is lower with 35 vs 40 inches. That’s why the engines produce the same or nearly the same as their naturally aspirated variants.

The other thing is most engines have an enriching valve which only comes on at max power, either by throttle position or manifold pressure. Operating at reduced power could mean a leaner and hotter mixture which could negatively affect engine health. I know that operating turbo charged planes that fuel flow was absolutely vital to check before take off.

Truth is a turbocharged twin is a poor aircraft for flight schools. I learned on a turbocharged twin and it was always difficult to keep from overboosting. It was a huge maintenance pig.

[Big Pistons Forever]

The Seneca 2 has a very simple fixed waste gate instead of the better but more expensive Variable Absolute Pressure controller used on the big block turbo charged Continentals. During takeoff as the airspeed increases the Manifold Pressure will also increase and therefore an initially acceptable MP can rise to an over boost condition. The fact that the MP gauge is buried next to the pilots right knee and thus hard to scan doesn't help matters.

The practical effect is that most schools teach the student to, at the beginning of the takeoff roll, initially set a takeoff MP well below maximum. Since most new Multi Engine students will be a bit behind the aircraft at first if the student neglects to monitor the MP during the takeoff the engine won't get over boosted.

When I was teaching on the Seneca 2 I told the students to set 35 inches at the beginning of the takeoff roll which will result in close to but under 40 inches MP at rotation. However I could easily see schools start walking that back even further in a bid to save the engines from the students, but without considering the impact of less than full power on takeoff in the event of an emergency

In any case and without judging this accident, I firmly believe that simulated engine failures during takeoff should never be done. The rewards do not justify the risks and the engine failure after overshoot exercise done at a safe ( ie 4000 AGL or higher) teaches all the skills needed to prepare a student for a real engine failure after takeoff scenario.

Personally I think the best Multi Engine trainer ever built was the Piper Apache. Very honest and forgiving flying characteristics make it pretty safe, but the marginal single engine performance requires a fine touch to keep it going up on one engine. If you can get the most out of the good old Piper Apathy you will be well prepared for when an engine dies on your grossed out Chieftain or King Air 100

[C.W.E.]

In any case and without judging this accident, I firmly believe that simulated engine failures during takeoff should never be done.

And any instructor who does do it should have their instructor rating suspended the first time and revolked the second time.

[pelmet]

The Seneca 2 has a very simple fixed waste gate instead of the better but more expensive Variable Absolute Pressure controller used on the big block turbo charged Continentals. During takeoff as the airspeed increases the Manifold Pressure will also increase and therefore an initially acceptable MP can rise to an over boost condition. The fact that the MP gauge is buried next to the pilots right knee and thus hard to scan doesn't help matters.

The practical effect is that most schools teach the student to, at the beginning of the takeoff roll, initially set a takeoff MP well below maximum. Since most new Multi Engine students will be a bit behind the aircraft at first if the student neglects to monitor the MP during the takeoff the engine won't get over boosted.

When I was teaching on the Seneca 2 I told the students to set 35 inches at the beginning of the takeoff roll which will result in close to but under 40 inches MP at rotation. However I could easily see schools start walking that back even further in a bid to save the engines from the students, but without considering the impact of less than full power on takeoff in the event of an emergency

This is exactly what I am talking about when I say "turbocharger issues".

Thanks for the details.

[7ECA]

In any case and without judging this accident, I firmly believe that simulated engine failures during takeoff should never be done. The rewards do not justify the risks and the engine failure after overshoot exercise done at a safe ( ie 4000 AGL or higher) teaches all the skills needed to prepare a student for a real engine failure after takeoff scenario.

I have an old copy of the multi-engine flight test guide (Seventh Edition - April 2010), in it is listed Exercise 10 - Engine Failure During Takeoff or Overshoot:

EX. 10 - ENGINE FAILURE DURING TAKEOFF OR OVERSHOOT

Aim

To determine that the candidate can maintain safe control of the aeroplane following a simulated engine failure during an overshoot and carry out the appropriate emergency actions.

Description

At an operationally safe altitude, the candidate will be asked to establish the aircraft in a final approach descent to a simulated landing in a landing configuration at the recommended final approach speed.

Once the approach is stabilized, the examiner will call for an overshoot and simulate failure of an engine as the candidate increases the power during the overshoot. (snip)

It's a bit odd that the old guide mentioned takeoff in the title, but then in the entire description of the exercise there is no actual mention of takeoff - just an overshoot. Now, in the latest FTG for the multi-engine rating (Ninth Edition, April 2017), the exercise is called "Engine Failure During Overshoot".

Maybe, for some bizarre reason this instructor decided to simulate failures on takeoff - because it was sort of in the FTG? Either way, it's a really stupid idea.

[7ECA]

This is exactly what I am talking about when I say "turbocharger issues".

Isn't this then a more widespread issue with all piston aero engines, naturally aspirated, turbo'd, supercharged, etc.?

Consider this scenario:

You taxi your mighty Cessna 152 out to the runway, at which point you come to a stop. Holding the brakes, you apply full throttle and take note of the engine/prop RPM, which is somewhere in the range of 2280-2380RPM. But, when you release the brakes and accelerate down the runway, good god man!, RPM increases up towards the redline of 2550RPM. I think this is a much more widespread "issue" than first thought...

[Big Pistons Forever]

This is exactly what I am talking about when I say "turbocharger issues".

Isn't this then a more widespread issue with all piston aero engines, naturally aspirated, turbo'd, supercharged, etc.?

Consider this scenario:

You taxi your mighty Cessna 152 out to the runway, at which point you come to a stop. Holding the brakes, you apply full throttle and take note of the engine/prop RPM, which is somewhere in the range of 2280-2380RPM. But, when you release the brakes and accelerate down the runway, good god man!, RPM increases up towards the redline of 2550RPM. I think this is a much more widespread "issue" than first thought...

For aircraft with fixed pitch props it is indeed important to know the static RPM range so that you can assure your self the engine is developing full power. However for normally aspirated engines with a constant speed prop or turbo charged engines with a Variable Absolute Controller or a Sloped Controller you put the throttle to full in/up and what you see is what you get. The Seneca 2's cheepo fixed waste gate controller is unique in that there will be a substantial rise in MP as the aircraft accelerates.

[pelmet]

This is exactly what I am talking about when I say "turbocharger issues".

Isn't this then a more widespread issue with all piston aero engines, naturally aspirated, turbo'd, supercharged, etc.?

Consider this scenario:

You taxi your mighty Cessna 152 out to the runway, at which point you come to a stop. Holding the brakes, you apply full throttle and take note of the engine/prop RPM, which is somewhere in the range of 2280-2380RPM. But, when you release the brakes and accelerate down the runway, good god man!, RPM increases up towards the redline of 2550RPM. I think this is a much more widespread "issue" than first thought...

For aircraft with fixed pitch props it is indeed important to know the static RPM range so that you can assure your self the engine is developing full power. However for normally aspirated engines with a constant speed prop or turbo charged engines with a Variable Absolute Controller or a Sloped Controller you put the throttle to full in/up and what you see is what you get. The Seneca 2's cheepo fixed waste gate controller is unique in that there will be a substantial rise in MP as the aircraft accelerates.

Funny....my reply was going to say ask BPF to give your some recurrent explanation of the basics, but........already done.

Turbocharger issues.

[youhavecontrol]

I started teaching as a Multi instructor last year and I've been eagerly awaiting the results of this investigation. It's sad to read that what most likely happened was what I feared might have happened. (at least, given all the evidence, even Transport Canada mentions it's the most probable cause) How on earth did they think practicing an engine failure during an actual take-off was a good idea? Was this normal procedure for the school? I've never heard of anything like that before. Our instructors are taught a very clear minimum altitude for us to practice this, as well as promptly taking control if the student gets below Vsse during the practice.

The process can be practiced perfectly at a higher altitude, with that added safety margin. Even the intensity of an engine failure unexpectedly during take-off can be replicated during simulator sessions... not in real life.

This whole event is just brutal.