The flight
test plan calls for for a significant disassembly and inspection after the
first flight. I should be an inspection similar in scope to an annual
inspection.
Only a few items needed attention after this first flight. One of them was
checking the calibration of temperature instruments, particularly the CHT
gauge. After un-cowling the engine, it was run up to operating temperature
and the non-contact infrared thermometer was put to use. This showed that
the CHT was not nearly as high as the instrument indicated, leaving the
question "HUH"? I needed to find out why so I could fix it. After spending a
long day, the short answer came along, and it was determined that the wrong
type probe was installed. Most CHT gauges are type "J" thermocouples, and
this Vans instrument, for whatever reason, required a type "K" ungrounded
probe. After finding a type "J" table and type "K" table on the internet, I
made up a cross reference chart for the cockpit, so I could keep flying
until the new probe arrived. FWIW, the CHT's ran at 380 during climb to 330
during rich cruise. Later testing would show temperatures around 390 deg F
during high power well leaned cruise. This is well within the 435 deg F
limit specified by Lycoming, and considering the warm summer Florida
weather, decided to be adequate.
A quick shot with the infrared thermometer to the engine accessory case and
oil filter housing showed the oil temp was accurate. The oil pressure was
high during takeoff but dropped into a normal range as soon as the engine
warmed up. I removed one washer from the regulating spring. The oil filter
was opened and found to contain an expected amount of crap, carbon, dirt,
rust, and metal particles. The filter was doing it's job.
All else checked out ok and the airplane was released for it's next flight.
The next flight was uneventful. I brought along a DVM to measure the
millivolts being produce by the CHT probe and confirmed the temperatures
from the lookup table were correct. The flight lasted 40 minutes and ended
uneventfully. Some initial cruise power and IAS measurements were take to
begin airspeed indicator calibration. Overall, the airspeed indicator read
3-7 knots low due to static port errors.
Later testing would carefully refine the performance and indication errors.
Still to be done would include a fuel fill up and refill to calibrate the
fuel flow computer |
Flight test 1