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Air Cadets grounded?

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Air Cadets grounded?

Old 28th Jul 2014, 21:21
  #181 (permalink)  
 
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BBK

Fair enough, mate. So why would you say the small sample size of 3x G-reg 109Bs have no rough running engine incidents when compared to a similar number of the mil-reg Vigis that appear to have a significant amount of incidents?

I know this is nothing to do with the 'pause', but I've often wondered why?

LJ
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Old 29th Jul 2014, 00:00
  #182 (permalink)  
 
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1.3VStall, Given the number of different aircraft types that the RAF has operated, and that A&AEE have evaluated over the last 94 years, is it not reasonable to try and avoid repeating past mistakes? If lessons can be learned, surely it is reasonable to prevent them being incorporated into new types to the service?

Leon, are the G-Reg Grobs doing circuits and bumps and are they using 100LL, 91/96UL or mogas? Maybe the way in which the Air Cadet aircraft are operated (the 12 minute circuits VX275 mentions) and 100LL makes them more susceptible to plug fouling?
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Old 29th Jul 2014, 10:28
  #183 (permalink)  
 
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AIUI the Vigilant is operated with the carb heat to hot for all but take off and landing due to the supposed aforementioned risk of carb ice.
That in itself will cause issues associated with running rich - rough running, wash oil off the bores and contaminate the engine oil, it has nothing to do with '12 minute circuits' (and just how big is a 12 minute circuit?).

Regular carb heat checks are taught elsewhere as a precaution against carb ice and if taught properly and with a certain methodology will not see carb ice being an issue (think O-200 carb ice problems, the CAA say it's the worst ice maker - if you adhere to regular checks it's not an issue).

Having flown a 109B on a day that was more conducive to carb ice than most I wouldn't say it has a tendency to ice up any more than, say, a C150.

And as an illustration of the lack of general aircraft knowledge and operation, I know of some of some Air Cadet instructors who insisted upon operating a privately owned aircraft with the carb heat hot all the time.


7700
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Old 29th Jul 2014, 12:17
  #184 (permalink)  
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LJ

I don't know the answer. I have some ideas but not the time to go into detail here.

Squawking 7700

"And as an illustration of the lack of general aircraft knowledge and operation, I know of some of some Air Cadet instructors who insisted upon operating a privately owned aircraft with the carb heat hot all the time."

Might that have been a Chippy where, I believe, the carb heat was wired hot in RAF use.

I've seen operations at 4 flying clubs and one VGS and and whlle all of them had the odd dodgy character for general bad practices the clubs were far worse than the VGS. I'm not saying it was the norm in the clubs but the VGS world take safety far more seriously, on average, than the clubs I saw.

No offence intended to the many good, disciplined club pilots out there. Read the accident reports if you don't believe me.

BBK
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Old 29th Jul 2014, 12:26
  #185 (permalink)  
 
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I remember the check on the Chippies at the Towers: "Carb air wired "hot""
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Old 29th Jul 2014, 12:58
  #186 (permalink)  
 
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I remember making the loop on the wire just big enough to slip on and off as required.........
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Old 29th Jul 2014, 13:00
  #187 (permalink)  
 
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There appears to be an element of incriminating VGS instructors when it comes to the use of carb heat and associating this with engine problems. I'm not sure what evidence these conclusions are based on?
Squawking7700, I have met and worked with many VGS instructors, who over the years have displayed exceptional knowledge in all areas when operating the Vigilant. Operation of the aircraft was always carried out in accordance with regulations in force at the time as I'm sure is the case today.
I would be interested to know what aircraft type you refer to regarding the instructor's use of carb heat at all times.
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Old 29th Jul 2014, 23:04
  #188 (permalink)  
 
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Leon, are the G-Reg Grobs doing circuits and bumps and are they using 100LL, 91/96UL or mogas? Maybe the way in which the Air Cadet aircraft are operated (the 12 minute circuits VX275 mentions) and 100LL makes them more susceptible to plug fouling?
Mechta

Same fuel from the same pump (100LL), same airfield but different airframes (ie. Vigi vs G109B). Thus I can't understand why the Vigi seems to have more incidences of a rough running engine than the civvy G109B? It is a small sample size, as I said before, of 3x G109Bs and 4x Vigis, but I can't remember any time over 3 years that the civvy 109Bs had a rough running engine at all - they've had a nose-over and a hard landing, but that's a different matter! The civvy 109B sorties are slightly different in that they tend to fly for 30 mins in the local area before coming back for a few glider circuits (normally teaching students how to deal with overshooting or undershooting glide approaches before going around for a further approach under climb out power). So I guess it could be the fact that VGS mainly fly circuits only, but I would have thought the problem would manifest itself on the civvy 109Bs at the same airfield over a 3 year period at some point? They do fly at least 12 hours a week and sometimes as much as 20 hours a week - in a year I would estimate around 4-500 hours across this civvy fleet. The only explanation I can think of is that the modification to the fuel system has something to do with it or that the FRCs/SOPs for the Vigi are different to the POH procedures for the 109B?

Of course, it could be that this particular VGS has had a run of bad luck with their engines or have the 'dogs' of the Vigi fleet?!! Or that the civvy 109B operator has been increadibly lucky?!!

As I said, I just dunno! It's just an observation and my own only plausible explanation as to why, that's all...

LJ
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Old 30th Jul 2014, 08:34
  #189 (permalink)  
 
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centrinoflyer & LJ - check your PM's


7700
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Old 30th Jul 2014, 10:06
  #190 (permalink)  
 
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A few years ago I spent a winter week at a Vigilant VGS supervising cadets on a course. While I can't remember the specifics I am sure that the SOP was to climb out 5kts lower than the book speed for "noise abatement" purposes.

This recollection doesn't seem to match with information plucked from a 109B resource on the Internet but it is quite a clear memory and I'd appreciate it if current crew could advise.

If this is true, could this be contributing to an increase in carb icing in the Vigilant fleet?
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Old 30th Jul 2014, 17:16
  #191 (permalink)  
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So why would you say the small sample size of 3x G-reg 109Bs have no rough running engine incidents when compared to a similar number of the mil-reg Vigis that appear to have a significant amount of incidents?
Probably because the civil ones are more likely to be wheeled into the hangar, sorted, and put back into use without a formal report going to the CAA.
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Old 30th Jul 2014, 20:09
  #192 (permalink)  
 
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Probably because the civil ones are more likely to be wheeled into the hangar, sorted, and put back into use without a formal report going to the CAA.
I would believe that if I wasn't at the airfield where they fly 5 days a week and would have noticed if that was the case! Nice theory, though.

LJ
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Old 7th Aug 2014, 15:09
  #193 (permalink)  
 
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"and just how big is a 12 minute circuit"

I suspect its not 'a' 12 minute circuit. More like 5 circuits in an hour from walk out to walk in, probably 2 to roll, 1 to land (taxi round to unscramble Bloggs' brains and give him another shottie at the Take Off Checks), then 1 to roll, 1 to land, and mine's with milk and two sugars.

Terrible shame if the entire AEF and VGS network is to be grounded for a while. But if its in the name of improving safety, who can argue.
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Old 7th Aug 2014, 16:40
  #194 (permalink)  
 
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One of my ones wasn't grounded at camp.



Thank you IV Sqn
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Old 8th Aug 2014, 10:38
  #195 (permalink)  
 
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From the noises heard over Truro over the last few days I would hazard a guess that the Tutors are up and about again?
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Old 8th Aug 2014, 10:46
  #196 (permalink)  
 
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Tutors have been back in action for a few months now but the gliding fleet is a long way from being back to normal.

Last edited by incubus; 8th Aug 2014 at 11:06.
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Old 9th Aug 2014, 07:24
  #197 (permalink)  
 
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Tutors have been flying for over a year now. Over 3000 cadet sorties delivered this year alone at a single AEF near me..!!
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Old 14th Aug 2014, 01:08
  #198 (permalink)  
 
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I had a look at Vigi FRCs and the advice on carb heat seems a bit 'wooly' to me - or maybe I'm just a grumpy old man? There seems to be some 'Carb Heat As Required', and also the following line, that is less than clear:

CARBURETTOR ICING If carburettor icing is suspected, use full carburettor hot air for 30 seconds. For optimum de-icing use a high power setting with the cabin heating at cold, An initial further decrease in RPM and an increase in rough running is usual during any ice melting process. It is recommended that carburettor air is selected to hot prior to any prolonged period of flight with low power setting, including within the circuit. Carburettor air should not be selected to cold before commencing the final turn but should at some point, be selected to cold before applying full power for a roller landing and, time permitting, before selecting power for an overshoot.
So maybe the increase in rough running on Vigis compared to G109Bs is due to the somewhat less than clear advice on the use of carb heat?

LJ
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Old 14th Aug 2014, 09:25
  #199 (permalink)  
 
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From deep in the memory, IIRC didn't the VGS use CIVGAS? which ISTR was 91RON, so quite a low octane and goodness knows what the water content was (is).

I thought that Ricardo got the job of sorting the power plant shortly after introduction to service?

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Old 14th Aug 2014, 10:32
  #200 (permalink)  
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LJ

You're looking at FRC in isolation to teaching manuals and SOPs. SOP is apply carb heat before level off, stays on unless full power climb is selected, then applied again before level off. Next time would be selected off is on final for potential go around. It is also used during taxi when conditions dictate. Can't use it more than that!

VGS don't use MOGAS is normal AVGAS
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