Jabiru J170 Weight and Balance

This is an example of how to complete the J120C Load and trim sheet. Remember to use the POH and figures for the specific aircraft which you are flying.

To complete this example you will need;

– Copy of your Aircrafts Load and Trim
– Your Aircrafts POH (Weights)
– a Ruler and a Pen

For this example we will use the following figures;

Pilot 90 KG
PAX front 65 KG
Fuel 100 LT (SG 0,72 = 72,0 KG)
MTOW 600 KG
BEM 362.5 KG
Empty Trim Index (CG) 62.56 (Empty Weight * Empty Arm) / 1000

STEP 1 – MTOW

Firstly, before going through the effort of using the trim sheet it is always advisable to add up your load to ensure that it does not exceed the aircraft MTOW. (However the trim sheet will show this)

BEM 362.5 KG
Pilot 90 KG
PAX front 65 KG
Fuel 100 LT (SG 0,72 = 72 KG)
TOTAL (RAMP) 599,5 KG
MTOW 600 KG

From the above we determine that the aircraft is within MTOW, however we still need to ensure that the CG is within limits.


STEP 2 – AIRCRAFT INDEX

In this step we will enter at the aircraft index as per our calculation above it’s 63.56, from here we will draw a line vertically down to intercept the first slanted lines representing the crew index.


STEP 3 – CREW INDEX

In this step we draw a horizontal line along the crew index units, crossing 1 diagonal per 10KG of crew. In our example 15,5 lines across, we then draw a vertical line down to intersect the baggage index.

STEP 4 – BAGGAGE INDEX

In this step we will move 1 diagonal across for each 5kg of baggage that we have onboard. In our example 10kg = 2 lines across and then we draw a line vertically down to intercept the fuel index.

STEP 5 – FUEL INDEX

In this step we will draw 1 line across for each 10L of fuel onboard. We will then draw a line vertically down across the envelope.

STEP 6 – EMPTY WEIGHT

In this step we will enter the chart on the right hand side at the weight corresponding to our BEM. In our example this is 362,5, from here we draw a horizontal line to intercept the crew ladder.

STEP 7 – CREW LADDER

In this step we will move down the crew ladder, 1 line per 10KG. Again in our example this is 155kg = 15,5 lines. Once we have found the bottom of the crew ladder we draw a line horizontally across to intercept the Baggage ladder.

STEP 8 – BAGGAGE LADDER

In this step we will move down the weight in baggage ladder 1 line per 5KG of baggage. Once again this is 10KG which is 2 lines. From the bottom of the baggage ladder line we now move horizontally across to intercept the fuel ladder.

STEP 9 – FUEL LADDER

In this step we will move down the fuel ladder 1 line per 10L of fuel. NOTE THAT THIS IS IN LITERS NOT KG. From the bottom of the fuel line we now draw a line horizontally across the envelope to see where it intersects the vertical line. As you will note the aircraft is just barely within the envelope, but this is to be expected with our RAMP Weight being so close to MTOW.

STEP 10 – CHECK ZFM

This is always a good step to take to ensure that the aircraft will be within the envelope for the entire trip regardless of how much fuel you have remaining.

Complete the steps above again but use 0 as your fuel quantity. See where the lines intercept, if they are still within the CG we have ascertained that the aircraft will remain within CG for all expected weights during this flight.

STEP 10 – FURTHER CONSIDERATIONS

Looking at the table in step 1 and the trim sheet in step 9 it is easy to see that if the aircraft was at full fuel in this example that it would be over MTOW and out of it’s envelope.

Don’t forget to check the aircrafts TORR against TORA at your airfield at the density altitude expected on the day.