Flight #22

6/2/16

Added 40 more pounds of water. This time to the baggage compartment. I’m walking the CG backwards a bit at a time from the 80.04 empty to the rear limit of 86.8. Takeoff for this flight was CG=84.3.

Basic Empty Weight LBS Arm Moment
Left Main

435

93.96

40872.6
Right Main

435

93.96

40872.6
Nose Wheel

296

39.11

11576.6
Empty

1166

93321.8
Empty CG

80.04
Max Limit LBS

1868.0
Max Limit Aero

1600.0
CG Limit Min

78.7
CG Limit Max

86.8
CG Limit Max Aero

84.5
Pilot Station

97.5
Passenger Station

97.5
Main Gear Station

94.0
Nose Gear Station

39.1
Fuel Station

80.0

W&B this flight @ takeoff:

Full Dummy 3
Empty Weight

1166

93321.8
Pilot

250

97.48

24370.0
Passenger

80 Water

97.48

7798.4
Fuel

252

80.00

20160.0
Baggage

40 Water

126.78

5071.2
Weight

1788

150721.4
CG

84.30
Left Main

736.5
Right Main

736.5
Nose Gear

315.0

Due to a visual on heavy rain to the west, decided to takeoff and stay in the pattern for 30 minutes. After 30 minutes of doing 8 takeoffs and landings in the pattern, it appeared the rain wasn’t moving in or getting any worse so I picked up the flight plan and departed to the west. Wind was from the east and keeping the rain to the west from approaching. Experienced rain in the RV for the first time deliberately during this flight since I could dart into and out of the showers (this was light rain falling from clouds high above). No apparent leaks. Flew along the edge of a line of rain with clear to the east (Fredericksburg) and rain showers to the west (Madison/Greene). Darting to the North allowed me to get out over Rappahannock to the west and circle Mom’s house for a bit.

Upped the G’s to 2.83 G’s max during a few maneuvers.

Times: 33.4/36.1 Before; 36.3/39.1 After

Flight Data

Flight Map

Rain pictures from the flight:

W&B @ Landing:

Landing Dummy 3
Empty Weight

1166

93321.8
Pilot

250

97.48

24370.0
Passenger

80

97.48

7798.4
Fuel

73.8

80.00

5904.0
Baggage

40

126.78

5071.2
Weight

1609.8

136465.4
CG

84.77
Left Main

670.1
Right Main

670.1
Nose Gear

269.7

Flight #21

6/1/16

Preflight, removed front air dams in front of the #1 and #2 cylinders. Still missing air inlet ramps. 80 lbs water in the passenger seat.

Starting Fuel: 40

Starting Time: Engine: 31.6, Total: 34.2

Flight Data

Flight Map

Increased G loading to ~2.7 G’s

Flew with 80 lbs in the passenger seat (2x 5 gallon jugs of water)

Ending Time: Engine: 33.4, Total: 36.1

Totalizer: 19.3 Used, 20.7 Remaining

Dip 11L/10R

Fill 18.9 Total

Flight #20

Preflight: Removed elevator bell crank inspection ports on both sides to inspect the elevator push/pull tube, jam nut, and bolt holding the elevator horns together. All was nominal. Added torque seal to the jam nut and elevator horn bolt so I can see if it ever moves. Reinstalled two inspection ports (7 #6 screws each).

Fuel starting was 20L/20R. Totalizer remaining: 40.

Oil was above 6.0.

Preflight: Engine: 29.9, Total: 32.4

I installed the passenger seatback which had been removed for many flights. I filled a 5 gallon gas jug with water (40 lbs), and strapped it to the passenger seat. Slowly beginning to increase the weight to explore the CG envelope. I did some stalls at 0, 1/3, 2/3, and Full flap settings near the beginning of the flight while the tanks were still relatively full. The stall behavior is slightly sharper, but still very benign. The AoA audio tone warning beeps are now active since I calibrated the AoA gauge last flight and it is a very nice feature.

I also spent a bunch of time leaning the engine and watching EGT readings…see the flight data link below and plot EGT, RPM, FF, and MAP.

Post flight: Engine: 31.6, Total: 34.2

Time: Engine: 1.7, Flight: 1.8

Fuel ending was: Gauge: 15L/13R. Dip 12L/10R. Fill: 7L/9.9R (16.9 total)

Fuel totalizer used: 16.9

Remaining: 23.1

Flight Data

Flight Map

The totalizer seems to agree well with the fuel truck. The gauges seem to read 2-3 gallons too high in the mid range.

Flight #17

5/28/16

Good flight all the way down to Massanutten and around Orange Co. This is the first flight where I started loading up the wing with G’s. I got to +2.4 G’s during this flight.

Preflight: Engine: 23.2, Total: 25.7

Post flight: Engine: 26.1, Total: 28.5

Time: Engine: 2.9, Flight: 2.8

Flight Data

Flight Map

Oil Pressure Sensor Fix

Worked on the oil pressure sensor trouble shooting today, and think I have found and fixed it. I found a bundle of wires entering the G3X EIS that when tugged caused the oil pressure gauge to fluctuate. Strangely with Mom and Rachel helping, we discovered that it also caused the fuel pressure and manifold pressures to wiggle also. Here is the text from my writeup on VAF:

VAF Post

I may be closing in on it
Ok. Far too many hours in the hangar tonight but finally may have found the culprit: enlisted help from my family to watch the gauges while I hunted for wiring problems. Finally found that tugging/bending the large bundle of wires going into the 78 pin connector on the eis caused the oil pressure gauge to do is jumpy thing

Surprisingly it also disturbed the gauges for the manifold pressure and the fuel pressure. Checked my wiring diagram and found the following wires in common among those three gauges:
Three grounds spliced together and three 5v lines spliced together and also sharing the 5v pin with the two capacitive fuel level senders.

The 5v and ground splices used those heat shrink solder bands and both looked only partially melted solder. I heated both and got much better solder flow. Put it all back together and gauges now steady when flexing and tugging same connector wire bundle. Will fly tomorrow and test. But I’m hopeful it is found.

Thanks Walt for the offer but I will wait and test for a bit more. I had tried swapping gauges without recal just to see but didn’t carry it to far or fly that way.

VAF Oil Pressure Post

VAF Post:

Ok this is driving me nuts. My new RV7A has 20 hours on it, and everything is just lovely…except this darn oil pressure intermittent problem where the oil pressure gauge suddenly pegs off-scale high (data download shows 155 psi, in abrupt change from minutes of nominal readings)

Here is a description, and what I have tried:

First cropped up after ~12 hours on new engine:

Kavlico 150 PSI 3 wire sensor (GND, 5V, signal)
0.5V = 0 PSI
4.5V = 150 PSI
Mounted on transducer block on firewall. Plumbed to the engine with a restrictor valve on the engine side of the hose.

Gauge will read fine: 50-60 PSI during taxi, 70-80 PSI during runup.
It will react normally and then just suddenly jump to 150PSI+. When it jumps there, it usually stays there while I terminate the flight. After engine shutdown, it stays reading pegged 150 PSI+. After avionics power cycle withe engine off, it will sometimes show 150+ and sometimes clear the error and show 0 PSI. If it crops up, it likely crops up in the first 10 minutes after engine start. If it doesn’t crop up, I can fly for 2 hours (2 times) and not have a problem.

The 2nd and 3rd time it happened, I landed, quickly removed the cowl and wiggled wires near the oil pressure sender…no change. I separated the connector near the oil pressure sensor (3 lines) and measured 0V GND, 5.01V, and 4.5 V on the sensor return line (this is with sensor disconnected)…Also, seem to have measured 0V GND, 5.01V and 0V on the sensor return line sometimes when I disconnect it (each time i disconnect, I do see a change from off-scale high to red X on display)…this made me suspect the sensor return line was somehow shorting to the 5V supply, or that it has a pull-up resistor in the G3X GSU73 that is pulling high when the gauge is disconnected.

So I spent 2 hours, digging under the panel and disassembled the connector shell at the GSU73 and checked all wiring…the only wiring i haven’t check is if there is chafing where it goes thru the firewall pass thru since that is covered in fire seal. With the GSU73 connector removed, none of the 3 wires seems shorted to each other.

This leaves me thinking I should try replacing the $90 gauge. but this is weird failure mode right? Could this be a firmware glitch that is solved by G3X firmware update. Could this be an intermittent GND line? When the ground goes away the pull-up brings the line high and thus the off-scale reading?

I also plumbed a mechanical gauge in parallel with the G3X Kavlico sensor, and the readings during a full runup are within 1-2 PSI from 0 to 50 to 80. But, since it seems i need to fly to get the glitch, I haven’t had the mechanical gauge plumbed during any of the actual glitch events. But I’m convinced it is not a real pressure event and it gauge or wiring…

Why would sometimes an avionics power cycle clear the error and return it to 0PSI if it was a wiring problem?

Any ideas would be much appreciated.