Sportcruiser - Opinions?

[patowalker]

Perhaps an honest mistake, perhaps creative marketing..

.

Which suggests that EASA simply accepted the manufacturer's figures, without checking. I bet the CAA enjoyed making EASA aware of the "mistake".

[IO540]

Which suggests that EASA simply accepted the manufacturer's figures, without checking

Surely, that is how certification works.

The manufacturer can forge the data.

I don't suppose Boeing would dream of doing it, because of all that hangs on it - a huge military and civilian business. But some small Czech firm which makes little apart from this little stuff...? The communist culture was one of dodgy dealing as a default.

[Mickey Kaye]

Didn't the CAA rain in on the good old Cessna 152 rate of climb numbers?

[patowalker]

Self-certification is accepted for the LSA category in the US, but the LAA, for example, insisted on witnessing a SportCruiser loaded to destruction, before granting approval. CZAW, was not happy to sacrifice another airframe, but they knew that LAA approval would make it easier to sell the model in other countries.

All UK home-built SCs had to go through a 5 hour flight test and all of them would have met or exceed the POH figures.

Can't say I enjoyed sitting in my handiwork while it was flung all over the sky by somebody who seemed intent on pulling the wings off

[A and C]

Performance numbers suspect, weak nose legs, cracking exhaust pipes................. not a good few weeks for the SC. On the whole a bit of a shame for what is quire a nice private aircraft.

However what is shows is that the price you pay for "light" is durability, this is why the SC is just fine in the hands of a private owner but using it as a club aircraft is a totaly different matter...................... now when are Lycoming going to STC the FADEC for the Cessna 152?

[smarthawke]

The C152 fleet in the Uk had a performance write down issued by the CAA some 10 years back. This took into account that the fleet was getting on in life.

The POH for a C152 states 'MAXIMUM' on the climb performance table page. So that'll be a factory fresh aircraft, company pilot and perfect weather conditions. Equalling (or even getting within the 70fpm shortfall allowed on a CofA air test) 'maximum' climb figures on a 5000 hr airframe and half life engine and prop was always going to be a tricky mission.

Not quite the same case as with the SportCruiser me thinks.

[flybymike]

I know nothing about Sportcruisers.
As a matter of course, do they always come with fixed pitch props of differing fixed pitches? or can they come with CSUs? or with ground adjustable only props? Electric adjustables? VP whilst airborne or only on the ground? or any combination of the above or something else?

[BEagle]

6 years ago, I had to recover a PA28 which had been force landed into a field. After much number crunching and careful measurement, I concluded that there was sufficient 'runway' available for the weight/met./surface/slope....

Even though it had a virtually brand new engine, the ground roll was rather longer than expected; fortunately, I had anticpated this and had an 'escape route' planned after lift off.

A few days later, we received a note from the CAA advising that this 30 year old design had performance figures some 10% in error! If I'd known the real values, I would never have attempted the take-off.

Now a 10% write-down is one thing, but to have to mulitply the performance figures by 300% in one case and 600% in another is quite ridiculous - how can the published figures for the SportCruiser have been so incorrect?

[Genghis the Engineer]

Certainly with an LAA or BMAA homebuilt, all those options exist in the market, giving the owner or builder a lot of options to choose from. But normally each variation is re-assessed for performance, handling and safety.

However, whilst LAA, BMAA and CAA will require that re-assessment, it looks like CZAW and Piper didn't see the need whilst EASA wasn't overseeing them properly.

G

[Genghis the Engineer]

Just adding to my post above, rather than amending it - a few of the issues that need to be considered in a prop change:

- Prop pitch is like a gearbox ratio, coarse = high gear, fine = low gear. So, a finer pitch will give better take-off and climb, but poorer cruise performance, and vice versa.

- Aeroplanes need a minimum safety margin between maximum level speed, and Vne, over-coarse props can degrade that.

- In flight test, we'll normally check climb and cruise performance first, if these are unchanged, then so should be take-off performance, which is a lot more work to measure.

- 912 series engines have the option to change gear ratio as well - increase the gear ratio and you increase loads on the engine mounts, so this needs re-assessing.

- If the prop diameter increases, then you may be increasing the risk of prop strike, so the geometry needs checking.

- Different prop configurations will put different propwash over the tail, which can change handling.

And so on, and so-forth.

G

[IO540]

A few days later, we received a note from the CAA advising that this 30 year old design had performance figures some 10% in error! If I'd known the real values, I would never have attempted the take-off.

Was this a grass surface and, if so, what correction did you apply to the tarmac figures in the POH?

IIRC, the CAA's flyer suggests adding 30% but that figure is straight out of the air. It could be 10% (short dry grass, a good smooth surface underneath) or it could be 50%... or more.

[Pace]

All this is all very well especially if you are renting aeroplanes but to a lot their aircraft is their own pride and joy.

Do you accept the book stall speeds or do you get the actual figures as well as behaviour on your own aircraft?

Two identical aircraft can be very different one stalls straight ahead wings level the other drops a wing etc.

If you know every burp your aircraft makes you will know how short a grass strip you can get in and out of how she handles wet grass, soft ground etc.
A PA28 30 years old with hangar rash, bad paint, a few bumps and bulges, a scattering of bugs over the wings and a knackered old smokey aint going to approach the book figures.

Know your individual aircraft and even work out your own actual figures.
In the case of new aircraft a lot is marketing. We know only too well the pre release figures claimed on the Diamond Twin Star 210 kts at 12000 feet on 135 hp???

Pace

[Rod1]

The LAA system is very good from that point of view. Every year the aircraft is test flown to a set schedule, normally by the owner, and the numbers and characteristics recorded. Stalls, testing to VNE, ROC etc.

Rod1

[Genghis the Engineer]

Originally Posted by Rod1

The LAA system is very good from that point of view. Every year the aircraft is test flown to a set schedule, normally by the owner, and the numbers and characteristics recorded. Stalls, testing to VNE, ROC etc.

Rod1

And the BMAA system, and the CAA Permit to Fly system - it's only EASA CofA aeroplanes that have gone away from the annual documented air test. This is a controversial topic in the airworthiness and flight test worlds: I'll freely admit that I sit firmly on the side of annual air tests, which I think are very good value for money if done properly by somebody with sufficient integrity and training in the task.

There is in my opinion a weakness in the LAA system in that it routinely allows owners, without special training, or oversight to do these air tests. I've certainly flown one or two of their aeroplanes where something went wrong and there were problems that most certainly should have been corrected before signing off a recent air test. BMAA and CAA work slightly differently.

I believe that these EASA permit aeroplanes are being dumped on CAA to manage, so they're treating them the same as CAA Permit aeroplanes and mandating the annual air test. That knowledge may well be where this CAA dictat has come from.

G

[smarthawke]

The Rotax gearbox ratio isn't quite as optional as might be deemed from Ghengis' post.

The 100hp 912S and 115hp 914 have a 2.43:1 ratio, the 80hp 912 is normally 2.27:1 with 2.43:1 as an option.

[733driver]

Annual flight test?

Genghis,

would you mind expanding a bit on why annual flight tests are done in the UK? I have never dealt with the LAA or BMAA etc and was wondering why, assuming the aircraft has not been modiefied, such a test woud be required.

Similarily I was wondering why certified airplanes do not require such a test (assuming there are good reasons to subject "amateur" built planes to them).

The way I see it: If engine, prop, airframe etc are unchanged and undamaged why the need for an annual flight test?

Looking forward to your reply!

[Genghis the Engineer]

Originally Posted by smarthawke

The Rotax gearbox ratio isn't quite as optional as might be deemed from Ghengis' post.

The 100hp 912S and 115hp 914 have a 2.43:1 ratio, the 80hp 912 is normally 2.27:1 with 2.43:1 as an option.

To be fair, there are far more options on the Rotax 2-stroke engines than the newer 4-strokes.

G

[Genghis the Engineer]

Originally Posted by 733driver

Genghis,

would you mind expanding a bit on why annual flight tests are done in the UK? I have never dealt with the LAA or BMAA etc and was wondering why, assuming the aircraft has not been modiefied, such a test woud be required.

Similarily I was wondering why certified airplanes do not require such a test (assuming there are good reasons to subject "amateur" built planes to them).

The way I see it: If engine, prop, airframe etc are unchanged and undamaged why the need for an annual flight test?

Looking forward to your reply!

The air test pre-EASA was done on all UK registered aircraft, although now is only done on Annex II aeroplanes. On PtF aeroplanes it's annual, on CofA aeroplanes it's normally every three years.

It's a check on performance - primarily climb performance for degredation outside of bounds set on the published data: rectification might be a performance write-down, check on propeller pitch, check on engine max revs.... A check on handling confirms that nothing's undesirably "drifted" since the last one (and I've certainly found a few of those, the worst I can recall was an LAA Aeronca Chief which needed about 15lb of left rudder to keep the ball in the middle and a BMAA Pegasus XL-Q which wouldn't fly hands-off and kept trying to accelerate into a 1000fpm dive). There's also a check that all the systems work: typical faults I've seen come up in air tests have been a window that kept coming open, an electrical generator that couldn't handle the lights and radios being on at the same time (that should have been picked up on the ground, but wasn't), excessive drift on a DI, a compass that was 45° out (no idea why the hell that wasn't picked up on the ground - I believe that the Chief Engineer subsequently had the chap who signed it off shot).

The logic is I think that certified "public transport" aircraft are subject to sufficient maintenance oversight that things can't drift off enough without being picked up and fixed, but that "private use" aircraft get less professional maintenance oversight that this is needed. There is some truth in this I think, although there are significant exceptions at both ends.

This is a fatal accident due to an under-performance PA28-140 that led AAIB to recommed to EASA periodic performance assessment of aircraft. So far, I think that EASA has ignored this, whilst UK CAA was doing it already.

G

[patowalker]

There is in my opinion a weakness in the LAA system in that it routinely allows owners, without special training, or oversight to do these air tests. I've certainly flown one or two of their aeroplanes where something went wrong and there were problems that most certainly should have been corrected before signing off a recent air test. BMAA and CAA work slightly differently.

The BMAA is seeking CAA agreement for owners to test fly their own aircraft. Something to do with a Pterodactyl, I believe.

The LAA conditions seem very reasonable to me:

1. Who Does The Flight Test?
The flight test must be carried out by a pilot who has studied the test requirements and is fully capable of carrying them out. Many owners prefer to do the flight tests themselves, and would not risk letting anyone else fly their prized machines. The minimum previous flying experience for the pilot carrying out the test is 100 hours total time including 10 hours either on type or on a similar or related type. Having said this, many pilot/owners with many more hours but out of practise at stalling, sideslipping etc do no feel confident about carrying out the tests, and prefer
to ask someone else to do this on their behalf. If you should be in this position, avoid the local 'ace of the base' whose experience in propping up the bar exceeds his actual competence with stick and rudder. Some busy owners are only too happy to leave the flight testing to the maintenance organisation carrying out the renewal, while some individual LAA inspectors regard it as part of their responsibilities to carry out the flight test themselves. It is up to the owner to talk this through with the inspector when the renewal is being organised, to come to a mutually satisfactory arrangement and fix up the insurance accordingly.

[smarthawke]

'To be fair, there are far more options on the Rotax 2-stroke engines than the newer 4-strokes.'

Apologies, Genghis - when you said this:

'912 series engines have the option to change gear ratio as well'

I thought you were referring to the 912s which are four strokes...

(PS Never have sussed how to do the 'quote' thing. Doh!)