EASA requirements: Exercise 1a: Familiarisation with the aeroplane: (A) characteristics of the aeroplane; (B) cockpit layout; (C) systems; (D) checklists, drills and controls.
Although it is not necessary to complete the entire PPL-theory course before we can start flying, we still need to have a basic understanding of how the aeroplane and it’s systems work.
Flight training can be done with almost any light aeroplane with two or more seats, and there are many to choose from. Initially it doesn’t matter much which one you choose. During this course we shall have a look at a few types and their differences.
We shall start with one of the most common of all trainers:
The Piper Tomahawk II
Specifically designed for flight training, almost 2500 were built between 1977 and 1982. Many flying clubs and -schools still use the Tomahawk today, because of it’s reliability and low operating cost.
From an instructing point of view, I particularly like its flying characteristics. Where most light trainers are build ‘extra’ stable to make it easier to fly, the Tomahawk requires proper pilot input, which makes it easier to see when you fly it the correct way, and also when you make a mistake.
In contrary to most other two-seat trainers, the Tomahawk is designed so that it does not recover from a spin without pilot input. But when the proper input is given, it will.
Note also that the Tomahawk has a better safety record than similar types.
The Tomahawk II variant has a few minor improvements, most notably the larger tires, giving a better propeller clearance, and better heating and soundproofing in the cabin.
Everything you need to know about this aeroplane is described in the POH, or Pilot’s Operating Handbook. It is a requirement for the Pilot of Command to study this manual before flight. But before you do that, let me show you some the most relevant features.
It is an all metal (aluminium) fuselage with a ‘monocoque’ construction, which means that the strength and rigidity comes from the outer skin. Before every flight we do a “walk around” to check the airframe for damage.
The cabin has two doors, two seats with seatbelts and harness, and dual controls. Compared to other two-seat trainers, the cabin is spacious and there is an excellent view outside.
Wings and control surfaces
The wing is designed by NASA, specifically to give the Tomahawk its flying characteristics. On the leading edge, a pair of stall strips were installed in 1983, to make the aeroplane compliant with the new certification rules and improve its spin recovery.
It has a low-wing design. As opposed to a high wing, this provides a much better visibility for the pilot, especially in turns. Low wing aeroplanes are in principle less stable than those with a high wing, but to counter this problem, the wings of the Piper-38 are mounted in a shallow V shape. This is called a dihedral wing and increases the roll stability.
The flight controls are conventional, and connected through a cable system.
The flaps are on the inner trailing edge. They are also controlled mechanically with a Johnson bar between the pilot seats.
The flaps are normally in the UP position. They can be extend by pulling the Johnson bar between the pilots.
- Flaps UP, gives the least drag.
- Flaps 21° (first notch) increase both lift and drag, good for a short field takeoff
- Flaps 34° (DOWN) Increases drag, to improve speed stability for landing.
The stall speed is only 3 knots lower with fully extended flaps.
The tomahawk has a T-tail. This design feature places the elevator outside of the prop-wash which reduces vibration in the control yoke.
The Lycoming O-235 is an air cooled, 4 cylinder piston engine which drives a two blade fixed pitch propeller. It delivers 112 HP at 2600 RPM.
Like most aircraft engines, it has twin spark plugs in each cylinder which are powered by a magneto system, making the engine completely independent from the electrical system.
There is a carburetor heat system to prevent ice forming on the throttle valve, and a mixture control to lean the mixture when flying at higher altitudes.
A tricycle, fixed landing gear supports the aeroplane the ground. The two main wheels have hydraulic disk brakes that can be operated independently. The nose wheel has air-oil type suspension. It is steerable via a torque link, which is connected to the rudder pedals in the cockpit
In the cockpit we find: Seats, yokes, rudder pedals and toe brakes, flap handle, 2 doors with lower and top latches, throttle, mixture, carb-heat, magnetos and a few other items.
The avionics can differ a bit in every other aeroplane. The basic instruments that must always be available for flying in visual meteorological conditions (VMC) are:
“Airspeed, Altitude, magnetic compass, RPM indicator and engine instruments and fuel quantity gauges”
Everything else is optional. Let’s have a quick look at what we have in our Tomahawk.
- the primary flight instruments, or “basic 6”.
- the ASI (Air Speed Indicator) indicates IAS (Indicated Airspeed), it is measured with the pilot-static probe under the left wing.
- The Attitude Indicator (AI) is a suction driven, gyroscopic instrument. It presents an artificial horizon and is required for flying in reduced visibility.
- The Altitude indicator translates barometric pressure into feet. The sub-scale needs to be set to the local pressure (QNH) setting to indicate altitude above mean sea level. In the States, Inch-Hg is used, in Europe Hpa. see conversion table.
- The turn indicator is an electric powered gyroscopic instrument and shows us the turn rate. The skid ball is a ball in a glass tube filled with oil and shows turn coordination.
- The Heading indicator is a suction driven gyroscopic instrument. If set correctly it indicates the direction or ‘heading’ of the aircaft, and is easier to read than the magnetic compass.
- The other instruments on the main panel are for radio navigation and will be explained in a later exercise.
- Engine instruments
- RPM is the rotational speed of the propeller and is a good indication of produced engine power.
- Exhaust temperature can give us information about the fuel/air mixture ratio.
- Oil temperature and pressure gauges are an indication of the ‘health’ of the engine.
- The Ampere and suction gauges show the status of the two systems that power the flight and navigation instruments
- Fuel quantity gauges should indicate if there is fuel in the tanks, and an estimate of how much.
Image: Altimeter setting conversion table
The electrical system is powered by an engine driven alternator and a 12v battery.
It feeds all internal and external lights, the pitot heat, the stall warning system, the electric starter motor, the electric fuel pump, the radio’s and some of the flight instruments. Electrical switches can be found on the lower side of the main panel, the circuit breakers are on the right hand panel.
The vacuum system is powered by an engine driven vacuum pump. It supplies suction power for some of the gyroscopic instruments, like the artificial horizon and the heading indicator. The system is independent from the electrical system to create redundancy.
The Pitot-static system
The airspeed indicator, altimeter and the vertical speed indicator are connected to the pitot-static system. On the bottom of the left wing you will find the pitot probe. On the aft fuselage you can find the static ports. The Pitot probe is heated to prevent blockage in icing conditions or heavy rain.
Stall warning system
On the left wing leading edge of the wing you can find the stall warning sensor. When the wing approaches the critical angle of attack, the metal tab will be lifted by the relative airflow and a micro switch activates a buzzer in the cockpit to alert the pilot.
Carburetor heat system
The carburetor is connected to the engine, this is where air and fuel is mixed and regulated by the throttle valve to set the required power setting.
In normal operation, air enters the carburetor via the air filter. Either when the filter is blocked, or when ice forms on the throttle valve, the engine will loose power.
By selecting the carburetor heat ON, the outside air bypasses the filter and is routed past the exhaust muffler. As long as the exhaust is hot, the air warms up and prevents ice buildup.
The engine runs on ‘Avgas 100LL’ which is Low-Lead Aviation petrol. It is stored in two wing-mounted tanks of 15 US gallons of usable fuel each.
A fuel selector control is located in the centre of the engine control quadrant. It can be set on the left or right tank or OFF. Fuel is pumped to the engine with an engine driven fuel pump. An additional electrical fuel pump is installed for redundancy. It should be ON for take-off and landing, and when switching the tanks.
Fuel pressure gauge, and primer are on the right panel.
3 fuel drains, one under each tank wing tank, and one by the fuel strainer, should be opened daily and fuel checked for water or other contaminant.
A detailed description of all systems can be found in section 7 of the POH.
Checklists, drills and procedures
A procedure is a sequence of handlings that are common to a certain phase of flight.
Some procedures are quite casual, like the setup of the radios before the flight. You can do them in any order you like, as long as they are done.
Other procedures require a strict order. As an example:
For parking the aeroplane: the drill is: Parking brake SET, 1000 RPM, Landing light OFF.
When levelling off after a climb: Power, Attitude, trim.
In most cases we operate the aeroplane completely from memory, but to err is human so we need a checklist to make sure that all critical items are set correctly.
There are normal, abnormal and emergency checklist, procedures and drills.
All Emergency procedures are described in section 3, and all normal procedures in section 4 of the POH.
Note that the ‘normal checklist’ in chapter 4 is actually the normal procedures. Most operators have made their own, abbreviated checklist for daily use. you can find the link to my variant here.
The introduction flight
That is enough theory for one day, now we are just going to make a short, 20 minute, familiarisation flight. During this flight I will be doing most of the work. I will be talking to ATC every now and then, and I will tell you a little bit about what I am doing.
The routing for today is the ‘standard departure’ via the south bank of the river clyde, Dumbarton and Alexandria, and the ‘standard arrival’ which is in the opposite direction via the north bank, to land back in Glasgow on runway 23.
After take-off I will trim the aircraft for straight and level flight and give the controls to you. I will do this by saying “Your controls”. After you reply with “My controls”, you have the aeroplane.
All we are going to do is fly straight and level, and perhaps if that goes well I’ll let you do a few turns. You can’t do anything wrong, I’ll be ready to take over at any time.
When I say “My controls”, you take your hands and feet off the controls and let me fly the aeroplane again, and you reply by saying “your controls”.
Do you have any questions so far? Are you ready? Let’s go!
AIS information for Glasgow airport is available here
Piper Tomahawk abbreviated Checklist (use at own discretion)
“Glasgow Ground, G-FIOL”
“G-OL start up approved, Information Charley correct, QNH 1021, standard exit not above 2000ft, report ready for taxi”
“G-OL Taxi via Whiskey to holding point Yankee 1 for runway 23”
before the next session:
In review of today’s flight, have a look at the POH, casually read though chapter 7 and the expanded procedures in chapter 4. See if you recognise anything from what you have experienced today.