MVF
The RAF dogs have box that measures the stress (or fatigue) that is put on the airframe and the life of the spar assembly is lifed acording to the mesurments from this box, so if you fly only S & L the readings will be low and the aircraft will last a long time.
The snag is that aerobatics is what the dog is all about and it is a very good aerobatic trainer and so is often mis-handed this all amounts to the fatigue life getting used quite quickly if you use the aircraft for what it is good at (it is not a good touring aircraft!).
I looked at a dog for the leaseing business that I have and talked to DH support about the re-life of the spar and it requires the replacment of a lot of bolts with oversize items and the reworking of the bolt holes, the problem is the manufacture of the bolts requires a production run to make it economicly posable, so without an order for say thirty bolt sets the price of the bolts exceeds the value of the aircraft.
The dog is not the only light aircraft with a fatigue life the PA38 has a 13000 hour spar life and some of the UK fleet of PA38,s have already been scrapped as they have reached the spar limit.
It's all very well trying to get around the fatigue issue and if it is your aircraft and only you fly in it then you take the risk of it coming apart in the air and except that risk.
For me with a business I have to provide a product that meets all the requirments of a public transport C of A afterall if I did not the lawers would have a field day with me in case the of an accident even if the spar life had nothing to do with the accident.
The bottom line is how much is YOUR life worth to you?
Last edited by A and C; 25th Jun 2006 at 09:17.