Building Pipistrel Sinus 912 Kit Serial 196

About Me
How this project originated
Purchase and shipping
FAA kit evaluation
Space, Tools and Materials
Fuselage Interior
Windscreen, top window and doors
Flight Controls
Landing Gear
Electrical System
Ballistic Rescue System
Rotax Engine Modifications
Firewall Forward
Instruments and Avionics
Final Details and Flight Preparation
Flight Test
Going Places
Supplemental photos and drawings
Engine modification photos from Pipistrel
Links and References
Flight Test

February 17th, 2013 - First Flight!

After a few weeks of waiting for my schedule and the schedule of Stan Kasprzyk, my test pilot, to coincide with suitable weather, things finally came together with clouds high enough and wind near calm for the first two test flights of Sinus 912 N54PK.  The only significant glitch is that the radio checks fine with the engine off, but with the engine running we're getting only a squeal and side tone from one headset and nothing from the other.  After trying various combinations of headset and cords, we resorted to a hand-held radio for the first flights.

We started with a general check of ground handling, braking action, low speed taxi and high speed taxi, with no problems.  The high speed taxi runs got up to about 25 knots, when the plane started feeling light on the wheels.  I had the tail wheel swivel detents rather tight on advice from George Powers, which prevented us from getting the swivel to break free for tight turns during the taxi tests, but the steering was adequate to turn within the available taxiway and ramp space.  I will reduce the swivel tension over the next few flights to find a setting that permits tight turns while retaining good control during takeoff and landing.

After a check for general integrity and leaks, we then flew the first flight, which went very well, indeed.  Stan did nearly all the flying, with me monitoring the engine parameters and assisting with the radio calls.  A local RV-12 builder flew chase and provided some in-flight photos. 

The plane flies superbly -- it has delightful handling, and flew straight and level with hands and feet off the controls. The engine is very smooth, with all temperatures and pressures comfortably in the green.  I flew most of the second flight, which demonstrated my very rusty flying skills, kept out of serious trouble by some quick intervention by the test pilot when I failed to adequately compensate for engine torque at the start of the takeoff roll.  I'll need further dusting off before I'm ready to solo.

Here's a link to Stan's web site, where he has a very nice write-up of the day's events.

And here's a link to a PhotoShow built by a member of our EAA chapter.

Many thanks to the Pipistrel team for producing great aircraft that is going to give me much enjoyment in the coming years.  I'm making plans to fly it to Oshkosh this summer.

Preflight briefing

Cockpit checks

Ready to go

Engine start

Ready for takeoff

Takeoff roll

We have lift off! Note the short takeoff roll.




Success! Test pilot Stan Kasprzyk on the left, me on the right.

February 17th to July 14th, 2013 - Phase 1 flight test complete: 43.8 hours

The Phase 1 flight test period proceeded in a very straightforward manner.  The normal lousy winter weather here in the Pacific Northwest, combined with the challenge of matching schedules between me and Stan restricted flying to one day in February (flights one and two), one day in March (flights three and four), one day in April (flights five and six) and one day in May (flights seven, eight and nine, including my first solo in the Sinus).    

We began with opening the flight envelope, first slow flight then high speed up to just below VNE.  Next came approach to stalls at all four flap settings, after which we focused on the landing pattern until I became comfortable, competent and consistent with the approach, flare, landing and rollout.  On flight eight we did the first in-flight shutdown, prop feather, a few minutes of gliding flight, unfeather and restart.  At the end of the flight Stan signed my log book for solo, to satisfy a stipulation by my insurance policy that required an instructor endorsement in the plane before soloing it.    

First solo


Flight nine was my first solo in the plane, which was a very satisfying feeling, fulfilling a lifelong dream to fly a plane that I built myself.  I was very grateful to have been able to benefit from Stan’s competent instruction to prepare me to complete the flight safely.  Total flight time at the end of flight nine was 7.8 hours.  There were no squawks on the plane during this period. 


The remainder of the Phase 1 flight test period consumed twenty-nine flights and 35 flight hours.  During this time I checked takeoff and climb performance, power on and power off stall speeds at all flap settings, accelerated stalls, glide performance (prop feathered), performed half-turn spins, and generally collected enough data points to confirm that the Pipistrel Sinus 912 Flight Manual applies to my aircraft.


I calibrated the Dynon fuel flow transducers, swung the wet compass and Dynon magnetometer (very consistent and accurate), flew the plane to a nearby avionics repair facility to have the initial transponder checks performed and logged in the aircraft log book (the first check of a new transponder installation includes connecting a calibrated altitude source to the altimeter static line and running the altitude up to the maximum height, checking the Mode C code at several points).


I disassembled the gascolator and checked the fuel filter a couple of times during this period, to see if I was picking up any debris from the fuel tanks as the initial few tanks of gas were flushed through the system.  I found only a very minimal quantity of small particles, so my careful vacuuming while grinding out the fuel cap openings appears to have done its job.  


The tailwheel steering and swivel action needed some work, so I re-greased the swivel plate, removed and greased the springs and steel balls for the swivel detents, and adjusted the detent screws until I achieved a suitable balance between positive steering and swivel breakout force.  After this initial lubrication and adjustment, the detent action has remained very consistent between annual condition inspections.



1. I found a small brake fluid leak at the fitting at the right wheel, which I fixed by tightening the fitting and re-bleeding the right brake. 

2. Dynon issued a recall for my Skyview displays, so I returned them for rework, although I never experienced any operating issues. 

3. The gas caps became difficult to turn for insertion and removal after a few hours, which I realized was due to swelling of the rubber o-rings that were supplied with the kit.  I found the o-ring size in the Parts Catalog (25.07 mm x 2.62 mm), and located an exact size replacement nitrile o-ring, which is a Caterpillar part OR46, available from Tornado Heavy Equipment Part as 1S7462.  Google is such a great resource!  The nitrile o-rings appear impervious to fuel, seal well and allow the fuel caps to be removed and installed easily.  I replace them once a year, although they exhibit no deterioration or wear in that time.

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