Building an RV with Jan Hanekom - Part Eleven
The maiden flight has been done and the party was a huge success - what now?
In the USA you have to fly your newly built RV for 40 hours before it can be signed out but here in South Africa we are lucky and usually you will get 25 hours for your proving flights with a 100km distance restriction during the proving flight phase. Even 25 hours can get very boring if you just fly to fly it off, but actually it can be a very interesting time and there is a lot to do and learn. By law the first flight and the last proving flight should be done by a properly rated test pilot but you as the builder can fly the rest.
Your builder manual has a lot of very useful information about test flying your RV. I will not repeat everything here, but please go and read it and use it as a guideline. Try and record your test results as you go along.
During your proving period you should include:
· Climb performance test
· Slow flight
· Stability tests
· Airspeed calibration
· Fuel consumption
· Prop evaluation
· CG loadings
· Performance checks
I would like to highlight a few points based on my own personal experience.
Post flight inspections:
It is very important to do a thorough inspection after every flight. I just cannot emphasize this enough. Remove the cowls and check all the critical fuel, oil en engine control items. The same for all the flight control systems and fasteners. It is not just an “eyeball mark one” check, but rather a “spanner in hand” check. Too often oil and fuel lines become loose where the builder will swear that he has tightened it properly and has also applied torque seal to it.
Just a few weeks ago an RV10 went down in the USA, in very rough terrain when the oil pressure sensor hose just came completely off in flight and ran out of engine oil. This happened after about 6 hours of flight. While the outcome is a testimony of survivability in an RV 10 and good piloting skills, it should simply not have happened!
One lucky pilot and one unlucky RV10
In another accident (also an RV10) the pilot reported loss of elevator control about 70 feet off the ground on final, slammed into the runway with lots of damage to the aircraft. Upon inspection they found that the bolt connecting the control column assembly to the forward elevator tube has fallen out. They could not find the nut - make your own conclusion on this one.
Depending on what engine you have in your new RV, the first five to eight hours will be mainly devoted to breaking in your engine. The engine documents that come with your Lycoming engine clearly state that “this engine had been run in at the factory and does not need any further run in”. We still use straight (ashless) oil and run it as hard as possible for the first five hours or so to make sure that it breaks in properly and that the oil usage stabilizes. The one thing you do not want to do is to baby your engine during the first few hours and sit with glazed cylinders and high oil usage.
All RV's built nowadays are equipped with digital engine monitors with recording capabilities. I can strongly recommence utilizing this. Download the recordings and study them after the flights as one can simply not remember everything. You will be surprised what you can learn from this and it is also very interesting. You can simply load all the data into excel or use one of many free online analyzers available. You will also find that you might go back to this data later on should you have a problem.
Personally I like Savvy Analysis. See . It is a very powerful tool and you can learn a lot from your engine by studying the graphs.
EGT against fuel flow graph example
An example of how you can use it is to look at the Delta CHT graph after your engine is run in properly. If you consistently see that CHT #1 and #2 are higher than the rest it usually means that the two little plates in front of the cylinders needs to be trimmed smaller. See the picture below.
Cylinder deflector plate
After the engine has been run in properly you can start doing all the other tests that is needed. I will not repeat the Van's guidelines here, but would like emphasize a few things. You have built a well proven design (8000 plus now flying) and things like stability tests and C of G tests should hold no surprises. Remember that all your test data as well as the given performance figures and specs by Van's will be used to compile your aircraft's POH (Pilot Operation Handbook).
Make sure that you do your airspeed calibration properly and know the stall speed in all configurations. Quite often one finds discrepancies here due to pitot positioning or leaks in the system.
Make sure you have calibrated your fuel flow (FF) system properly. I find that a well calibrated FF is worth a lot later on when you use your RV on those nice long cross country flights. Make sure you know how long you can safely run on one tank and what your RV's real unusable fuel is.
Avionics and other systems:
With all the fancy glass cockpits we have nowadays one should not under estimate the effort needed to properly set up your system. First make sure that you know your system the best you can before you start changing the default settings. Start with the most important ones like the engine monitoring stuff and progressively move through all the functions.
You will have to among other things:
· Set up airspeed limitations such as VNE
· Set up all sensors
· Set up mapping features - you might have to purchase mapping databases
· Do proper compass calibrations
· Setup auto pilot settings and adjustments if installed
· Setup all warning limits on the EMS ( Engine Monitoring System)
Do a thorough job of this as it will make your life much easier later on and believe me there can be surprises should you not study the manuals. Here is an example of such a surprise. After I have done the ground testing of the AP ( Auto Pilot ) I proceeded to adjust the in flight setting while flying at about 120kts ( slowish cruise ) and every time I engaged the pitch servo, this RV would pitch up quite sharply. After some head scratching and more reading I found a setting, deep into the menu layers where it is said “pull below xxx kts”. This was set at 140 kts for some reason! Therefore when you engage the AP below this speed it will pull up automatically.
Typical glass cockpit RV10
Well this is the end of this series and I hope that you have found it positive and that you could take a few ideas from it.
From the Pilot's Post team:
Jan, your series on building an RV was truly exciting, informative and enjoyed by all of us. I am sure that for years to come, builders will continue to return to learn and to be inspired by your commitment, passion and perfection.
We truly appreciate all the information you shared with us in this series and the information you will still share with builders in the future.