Amateur-built and experimental aircraft - Australian Transport Safety ...

Source: Falco Builders Newsletter December 2001
The technology in ABE aircraft engines largely reflects engineering principles from
the pre World War II era. They tend to be favoured by ABE aircraft owners and
builders because they are a known and tested quantity, not necessarily because they
are as efficient as modern engines (Wanttaja, 2006c).
Some people in the survey commented on their experiences with engines. One
person said:
I fitted an auto conversion and this was not successful. I am replacing the
engine with a Lycoming. The moral is aircraft should have aircraft engines.
In order to get a better climb rate, one respondent changed to a radial engine, while
another respondent talked about getting assistance with automotive conversion.
Advanced aircraft features
Aircraft with a manual propeller pitch control (MPP) 32 or retractable undercarriage
are considered more complex aircraft, and they require licence endorsements. This
question was a multiple response question; 387 responses were received. The
proportion of respondents who reported their aircraft had one or more advanced
features is shown in Figure 32. This shows that the majority, about 60 per cent of
aircraft in the survey, did not have complex features.
Of the 40 per cent that were complex aircraft, the manual propeller pitch control
was the most frequently cited characteristic (34 per cent), while about 15 per cent
had a retractable undercarriage. Nearly 10 per cent had both a manual propeller
pitch control and retractable undercarriage.
Figure 32: Complex aircraft by aircraft characteristic
A retractable undercarriage can be a challenge to build because of multiple linkages
and hydraulics, but it offers better aircraft performance and less drag in the air when
compared with a fixed tricycle undercarriage. One challenge associated with
retractable undercarriages is when the pilot receives a warning that the
undercarriage has not properly extended or only partially retracted. In this
circumstance a pilot must manually lower or retract the landing gear, seek
confirmation from a person on the ground as to whether the gear is down, or
possibly land with the gear in the up position. A manual propeller pitch control
allows the pilot flexibility to maintain an optimal angle of attack on the propeller as
aircraft speed varies (Kumar, 2005). Under CAO 40.1.0, special design feature
32 A manual propeller pitch control refers to a controllable pitch propeller as opposed to a fixed pitch
propeller. They are also referred to as variable pitch propellers (VPP) or constant speed unit
(CSU). The survey used the term ‘manual propeller pitch control’.
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