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Current Thruster Accident Trends

Guest TOSGcentral

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Guest TOSGcentral

The following is a brief appraisal of current operational trends in Thrusterworld as applies to bending things and scratching the paintwork.



In the airworthiness related area there is (as usual) nothing of note other than the Yarrum TST Tailplane failure. While this was scary, TOSG are not viewing the situation along the lines of ‘everyone has got to buy new tail planes’! Equally, the matter should be taken seriously and the RAAus inspection and tailplane tensioning AN followed. At the moment you are grounded until that procedure has been complied with, then signed off in the aircraft’s log book!



The significant point is that while we do not yet appear to have a general fatigue problem that is specific to type – you may not know what exactly happened to the aircraft before you bought it! The area of failure appears to be a ‘conditional weak area’ that could be triggered by prior trauma to the airframe. Just check and then relax – it is a once only inspection although I will be having my tail units off for a look every 100 hours.



On the AN subject – remember that there is a standing AN for 50 hourly inspection of the ventral portion of the fin for fatigue cracking of the chromealloy tubing on TST, T300 and T500 models. TOSG strongly recommends that this is voluntarily introduced to 50 hourly inspections of the Glasshouse, Gemini X, A & B models. While these are all alloy they are subject to loosening of rivets and/or fracture of rivets or the metal – particularly immediately aft of the boom where there is a maze of rivets to connect various parts of the structure together.



If a ventral portion of the sternpost snaps then you will lose all directional control from the tailwheel. If this happens during take-off or landing then you are going to have one helluva operational challenge!



In pure flying operations most of the ‘traditional’ major accident areas that comprised belly-ins following engine failure after take-off, or during the initial climb, have generally seemed to have faded away. This is probably due to continual promotion of energy awareness v’s drag in that phase of flight that TOSG has been beating the drum about now for years.



Having said that, what is less impressive is that we have had some comprehensive stack-ups that you have not read about in the magazine. One that I am currently working on is a T300 that went through power lines. It is being rebuilt but just about every major bit of it’s structure has to be replaced.



Another is a TST that sounds as though it was at max take off weight when the pilot lost control of it on take-off during the take-off roll and went through a fence. The aircraft is an economic write-off although there were no injuries of much consequence.



This sort of thing is just not acceptable! Providing you are on top of the initial power application swing, and you are operating within the aircraft’s cross wind limits, then a Thruster is so easy to take off.



As always, the landing phase is the most vulnerable in a Thruster (until we have this angle of incidence sorted out that will tame it considerably). The only solution to this is pilots being correctly trained on taildraggers and then operating within their own, and the prevailing conditions, tolerances!



What you can also do (and this is NOT a sales pitch) is get tail unit formers fitted if you do not have them. The additional control power will be of significant value to you.



I will shortly be following this post by another to discuss wheel on landings v’s 3 pointers – so let us get some frank discussion going.









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