Well, for your information, behind the scenes I've been putting together - with the aid of information furnished by two of the posters to this thread - a formal case. It all reads at my pompous best, which CAA generally like. It's just gone in the post to davidhenson, so next stage is for him to present it to Gatwick and see what response he gets.
G
Main text of the letter...
Description of the aircraft
The Vigilant T1 is a single engine side-by-side all-composite tractor monoplane. It is fitted with a single air cooled engine derived from a VW automotive engine, to which is fitted a 2-position Hoffman 2-blade 1.6m diameter variable pitch propeller.
The aircraft is derived from the Grob G109b which is eligible for issue of an ICAO compliant certificate of airworthiness as a touring motor glider. However, the aircraft is modified from the G109b in the following ways:-
- Provision of personal parachutes as standard equipment
- Increase in MAUM from 850kg to 908kg.
- Different instrumentation.
- Different operating limitations.
The eligibility of the Vigilant T1 for issue of a CofA as a powered sailplane
There is only one standard used within JAA states for issue of a CofA to a glider or motorglider. That document is JAR-22 which at part 22.1 Applicability includes the following definition at 22.1(a)(2)…
Single engined (spark or compression ignition) powered sailplanes the design value W/b² (weight to span²) of which is not greater than 3 (W[kg],b[m]) and the maximum weight of which does not exceed 850kg.
Whilst it may be shown that the Vigilant meets the W/b² requirement, the MAUM at 908kg exceeds the 850kg limit for certification as a powered sailplane.
The aircraft would therefore not be eligible for issue of a CofA as a powered sailplane under current rules as accepted by JAR.
Considering the Vigilant T1 as a Touring Motor Glider (TMG) or SLS (Self Launching Sailplane)
The Vigilant T Mk.1 does not have any mechanism to retract the engine and/or propeller when not in use (although it can be feathered). This is an essential pre-requisite of an SLS, therefore the Vigilant T Mk.1 does not fit into this category.
It is a requirement to be classified as a Touring Motor Glider (TMG) that an aircraft can take-off unassisted. This is defined in JAR 22.51 as being able to attain a height of 15m in no more than 500m when taking off from a dry, level, hard surface. This distance, as given in the operating data for the Vigilant T Mk.1 [ ] is 655m. Therefore within the definition accepted within JAR regulations the aircraft is incapable of taking-off unassisted. It should be explained that this was understood and accepted by the Air Cadets organisation since it operates from military airfields with sufficiently long runways that this does not create an unacceptable hazard.
Therefore, the Vigilant T Mk.1, although safe in operation as a military training aircraft does not meet the safety (field performance) standards required of an aircraft which might be used as a civil motor glider.
Justification of the Vigilant T Mk.1 as a Single Engined Piston Aeroplane
It is, as discussed above, my opinion that hours logged flying a Vigilant T Mk.1 cannot be considered to be either Self Launching Sailplane (SLS) or Touring Motor Glider (TMG) for the following reasons:-
- The MAUM is too great for eligibility under JAR-22, which is the basis for issue within JAA states of an ICAO compliant CofA as a powered sailplane.
- Neither engine nor propeller retract, therefore the aircraft cannot be considered to fall into the SLS class.
- The aircraft’s take-off performance is too great for it to be considered able to take-off under it’s own power, as defined in JAR-22.
Nonetheless, it is undeniable that the aircraft is a single piston-engined fixed-wing aeroplane in which flying is carried out, legally, in the United Kingdom. The only other class of aircraft overlapping with SEP is microlight, which permits only an MTOM up to 450kg for landplanes and is therefore clearly unsuitable. It is therefore my recommendation that pilots legally flying this aircraft, under supervision of RAF HQ Air Cadets should be permitted to log hours flown in this class of aircraft in the “single engine piston” class.
I would also like to note that the aircraft has a tailwheel (rather than tricycle) configuration, and a pilot controlled 2-position variable pitch propeller. There is therefore a strong case for suggesting that any pilot qualified by the Air Cadets to fly as pilot in command of a Vigilant T Mk.1 may also be considered to have completed differences training in tailwheel configuration aircraft and in the use of variable pitch propellers – it is my recommendation that they should be credited with this.