JABIRU Standard Practice

Transcription

1 JABIRU Standard Practice Aircraft ing Procedure 1. Introduction Measuring the correct weight and determining the correct location for the center of gravity for your aircraft when it is empty is an important task that must be done after the aircraft is fully built and before it can be allowed to fly. This leaflet describes the method recommended for weighing an aircraft and calculating the location of the center of gravity. Data derived using this procedure can be entered into Section 6 of the Flight Manual, or Owner s Manual and can be used as the starting point when checking the weight and balance of the loaded aircraft CHECK In some countries regulations require that a person who is an approved Aircraft t and Balance Authority must supervise the weighing and the calculations. Check with the authorities to see what regulations apply to your aircraft. 2. ing Procedure ing an aircraft is not a complicated procedure but it does require careful attention to make sure that each step is done properly and that all measurements are made accurately. The aircraft has to be in a known condition when it was weighed. This should be in the condition with all equipment on board, full engine oil, and all fuel drained from the tank. This also includes the little things like headsets, upholstery, and manuals. If you plan on having a first aid kit in the aircraft at all times, then this should be included as well. The aircraft must be in a level attitude when the weights are recorded so if you have to put the aircraft up onto the weighing platforms, do a trial run to make sure that you can level the aircraft properly when it is up on the scales. You should repeat the weighing procedure two times and compare the sets of readings. This is one way of checking to see that there are no obvious errors. JABIRU recommends that there should be a weighing platform under each wheel so that the weight on all of the wheels can be measured at the same time. Other methods where a single weighing platform is rotated around the wheel are not endorsed they can lead to errors. PAGE 1 OF 1

2 2.1. ing Procedure Item Action 1. Check that the aircraft is complete and that all of the equipment is installed in the aircraft 2. Check that the engine oil is filled to the maximum level. Check that the fuel tank has been drained. 4. Set Up the ing Scales: Check correct function: Check the zero reading. 5. Place the aircraft onto the scales for the FIRST WEIGHING. 6. Level the aircraft using one of the procedure provided in the Constructors Manual 7. Record the weights on all three wheels, in the first weighing section of the AIRCRAFT WEIGHING CHART included at Appendix 1 to this leaflet. 8. DO NOT MOVE THE AIRCRFT OFF THE SCALES YET 9. Mark the Reference Points on the Hangar Floor and clearly identify them as 1 st Drop a plumb line from the RH Wing Leading just outboard of the wing root fairing Drop a plumb line from the LH Wing Leading just outboard of the wing root fairing Mark the position of the center of the RH main wheel on the floor. Mark the Position of the center of the LH main wheel on the floor Mark the Position of the center of the Nose wheel on the floor. Notes: if the floor is smooth and level you can uses a builders square to mark the wheel centers on the floor. If this is not the case, you will need to drop a plumb-bob line down to the floor from the center of the axle. It is a good practice to mark both sides of the nose wheel as the wheel may not be properly centered. Make sure that these marks are on the ground and not on the weighing platforms that could move when the aircraft is pushed off. 10. NOW YOU CAN MOVE THE AIRCRAFT OFF THE SCALES 11. Measure the Distances between the wing Leading and the and record this in the Aircraft ing Chart. Draw a line on the ground between the two LR, and RH wing leading edge points that you marked on the ground in this first weighing using a suitable straight edge or a chalk line. Draw a line on the ground between the points that you marked from the LH and the RH sides of the nose wheel with a straight edge. Measure the distance between the center of the nose wheel line, and the wing leading edge line. Record this measurement in the WEIGHING SUMMARY CHART 12. Repeat Steps 5 through 10 for the SECOND WEIGHING, make sure that you identify the points that you mark on the ground as 2 nd otherwise it can get very confusing 1. Go on to do the Calculations 2.2. t and Balance Calculations If you have access to a computer then these calculations can be done using a MICROSOFT EXCELL Spread Sheet. You can contact your Distributor for a copy of this program. PAGE 2 OF 2

3 If you do not have access to a computer then you will need to follow the example and complete the EXAMPLE CALCULATIONS Step 0. This is how you Chart should look after you have finished the weighing. MeFr as o ur m ed WiEd Di ngge st Le an ad ce in s g Index Index EMPTY WEIGHT INDEX There should be numbers in the boxes for the first and second weighings. ts to be Used Combined t on s LH RH LH RH LH RH PAGE OF

4 Step 1 You need to find the average value for the weights and distances in each of the five columns, C=(A+B)/2 C=(A+B)/2 ts to be Used C Index Index EMPTY WEIGHT INDEX Combined t on s LH RH LH RH B LH RH A B A C Step 2 Add the weights from the two main wheels together. D=E + F ts to be Used Index Index EMPTY WEIGHT INDEX Combined t on s LH RH E D F LH RH LH RH PAGE 4 OF 4

5 Step Transfer the Nose wheel weight up to the box H. You don t have to do anything to the number. H= G ts to be Used Index Index EMPTY WEIGHT INDEX Combined t on s LH RH G H LH RH LH RH Step 4 When you weighed the aircraft you made measurements with respect to the Wing Leading. The actual datum is 140- mm in front of the aircraft so you will need to adjust the values as if they were measured from the aircraft datum. K = J ts to be Used J K Index Index EMPTY WEIGHT INDEX Combined t on s LH RH LH RH LH RH L M M= L PAGE 5 OF 5

6 Step 5 and the ing Index s. P = D * K ts to be Used K Index Index EMPTY WEIGHT INDEX P Combined t on s D M LH RH LH RH S H S = H * M LH RH Step 6 aircraft Empty t Index by adding the s for the and. Empty t by adding the Main wheel and Nose Wheel ts ts to be Used Y 45 = P S Index Index EMPTY WEIGHT INDEX P Combined t on s D S H LH RH LH RH LH RH V = D + H Y V PAGE 6 OF 6

7 Step 7 Aircraft Cg location ts to be Used Index Index EMPTY WEIGHT INDEX Combined t on s LH RH LH RH Z=Y/V Y V Z LH RH Finish These are the three numbers that make up you empty aircraft weight and Balance Data ts to be Used Index Index EMPTY WEIGHT INDEX Combined t on s LH RH LH RH LH RH PAGE 7 OF 7