How To - Handling

[Eddie]

Approach and landing best practice

The best practice when on final approach in a light twin aircraft is to fly at a speed at or above the blue line speed (104-108kt depending on altitude). This speed is called Vyse, or best rate of climb speed with one engine inoperative. At this speed the aircraft has the least amount of drag in an engine inoperative situation.

In the F406 it is recommended to approach at 130kt, this higher speed provides better control and improved forward visibility. It also gives a margin to Vyse should an engine failure occur during the approach.

Continuing the approach, you would maintain 130kt until you are committed to land. This shall not be confused with being below the decision altitude for your approach. For example, you can be below your minimums but the aircraft ahead is still on the runway and has not vacated yet. Once the runway is clear and you consider yourself committed to land, reduce speed, aiming to reach Vyse by the runway threshold. If you want to do a short field landing you can slow down further, but never below red line speed (90 kt) which is your minimum control speed in the air (Vmca) with flaps in the take off position. A single engine go around close to Vmca requires very precise flying to avoid losing control of the aircraft.

Engine failure handling

Handling an engine failure in a light twin aircraft such as the F406 requires precise flying and diligent adherence to procedures. 
Compared to airliners, there is no automation to assist in handling the assymmetry (such as automatic rudder trim) and the amount of excess thrust provided by the operating engine is significantly less.
The steps required to handle the failure can be remembered as: Power Up, Clean Up, Identify, Verify, Secure. 
Lets discuss each step in more detail.

Power Up

Losing an engine is a serious issue, and can lead to an 80% or even greater loss of performance. When the failure is detected, immediately select the maximum propeller RPM (1900RPM) and maximum power (1385 ft-lbs torque). At this stage move both engine propeller and power levers, the priority is to get the maximum amount of power and not to spend precious time choosing what lever to move.

Clean Up

Given that performance is greatly affected, flaps must be selected up and the gear retracted in order to reduce the amount of drag.

Identify

To identify the failed engine think of the following sentence: “Dead leg, dead engine”. The rudder input will always be in the direction of the live engine. If the left engine fails, the aircraft will yaw to the right, requiring the pilot to input left rudder. This leaves the right leg “dead” and not doing much, this is the first step to identify what engine has failed.

Verify

Mistakes can always happen and the next step is to confirm that the initial failed engine assessment is correct. The engine instruments will serve as confirmation that an engine has failed. Following the positive confirmation of what engine is failed, the power lever of the affected engine is slowly retarded to idle. There should be no change in yaw If the identification of the failed engine is correct.

Secure

The final step is to secure the failed engine. Positively identify the correct propeller lever and feather it. Continue on to the fuel control lever and select it to cut off. Turn the generator off and the fuel boost pump to off.
The failed engine is now secure.

A final step that aids in handling the aircraft is to “raise the dead”, roll the aircraft approximately 5 degrees towards the live engine. Keep the aircraft flying straight, the slight bank will give a lateral component of lift that will be in the same direction as the rudder input allowing the pilot to release a bit of rudder.

Climb considerations

The F406 is unpressurised, and care should be taken to ensure passenger comfort.
To avoid discomfort, the vertical speed of the aircraft during climb should be maintained around 500-800fpm. Power should be adjusted in order to achieve the required climb speed and rate of climb. Maximum continuous power might not be adequate, especially at lower levels where there is a lot of excess power available.

Descent considerations

The human ear is more sensitive to increasing pressure during descent compared to the decrease in pressure experienced as the aircraft climbs. During descent it is recommended to maintain a vertical speed not greater than 500fpm.
This requires a different computation of the top of descent point based on time required to reach the desired altitude.

Lets assume we are cruising at 10,000ft and we want to descend to a target altitude of 2,000ft. 10,000 - 2,000 = 8,000ft descend. At a rate of descent of 500fpm this will take 16 minutes. 
Once the amount of time required is known, we need to know the ground speed of the aircraft, for our example we will assume 180kt, which is 3nm per minute. Multiplying the time required to descend by the amount of miles covered per minute will give us the distance of the top of descent point. 16 x 3 = 48nm. The descent should commence 48nm before the point at which we would like to level off at 2,000ft.