Navajo Spar Mod - Can we drop it yet?
No good talking to Steve Swift ... he'll just send you on to me. In the first instance I'd worry more about the J2BDs. Possibly the worst piston engine in the world, and you are looking at 100K a side. Piper did the original fatigue assessment and it was they who put the life limits on it in accordance with the requirements from CASA. It was designed as a corporate aircraft, and Piper thought 13,000 hours good enough - they could have done better.. Nobody foresaw Reg 203 exempt ops and by 1989 (yes 28 years ago) there were time-x chieftains pushed up against fences everywhere. Come the pilots strike - everybody wanted a mod, and that was what gipps did. We moved it across from fatigue to Damage Tolerance and everybody (including Max Hazelton who I think had 20 plus) was happy. Sure you can get the AD rescinded just get piper to provide CASA with the relevant information. It is no different for Boeings or Pipers - what the manufacturer says goes unless you can find some poor underpaid bunny to recrank the numbers. And you will need a cuppla mill to do that. Mahindra no longer does the mod - mostly I suspect because of sentiments like the above. I'd have a long hard look for corrosion especially between the lower spar cap and the thick splice plate and study up on detonation
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Possibly the worst piston engine
No good talking to Steve Swift ... he'll just send you to me. I'd be more worried about the J2BDs .. $100K aside. The AD is based on data supplied by Piper as the manufacturer. There is no difference between Boeings and Pipers. CASA writes the requirements and Piper gives the data. It was a corporate aircraft. Piper did a simple test and came up with 13,000 hours for the -350 - it should have been better but Piper did not want to revise it. That is the way it is unless you can get some underpaid bunny to recrank the calculations. That was not going to happen until the pilots strike in 1989. Even then (28 years ago) there were timeX PA31s pushed up against fences. Rather than do a fatigue test again, it was taken across to safety by inspection and all those timeX were back in service. There were a lot of happy faces, particularly at Hazo's who had twenty odd. The FAA have found cracks in a Chieftain spar cap (not good). I suspect it was a "Friday arvo" aircraft ... I found a couple. They do have corrosion problems. ... And I'd learn a lot about detonation ... 100LL can't last forever.
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In over 4000 hrs and 8 years with TIO540's, I found them very reliable, to the point of never losing one, had maybe 4 or 5 dead cylinders in all that time. And we worked them pretty hard. But we looked after them, and had good guys looking after them.......
Last sentence is the key. EDMs are essential, but they can only tell you what happened while the EDM is fitted. and I must admit it has nothing on the TIGO 541 for cost
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Just recently a ndt check was carried out resulting in cracks found in the modified spar. As a result ive been infromed that casa is now looking at the modified spar and talk is now grounding aircraft with this mod.
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Firstly, thanks to aeromariner for illumination. I didn't know the history.
So in the US are they replacing spar caps as per the Piper-approved way of extending wings for another 13,000 hours (-350)? Or just parking them as per original Piper approved method.
Why go for the red button straight away? Wouldn't it be more prudent to check other planes out first?
And I second those that have defended the J2BD, a good engine that is highly intolerant of ignorance. This ignorance was not only the throttle jockeys but also from the heavens of 'approved' sources, refer the Climb Power Leaning Chart in the AFM
100LL won't last forever, no, but I'm pretty sure George Braley has been feeding J2BDs G100UL with fine results!
And comparing PA31 to C208 was done on purpose to try and keep the 'piston twins should be banned' folks at home. A lot of good businesses come from a great idea that then earns money. Not from a lot of money looking for an idea.
RFDS didn't start out with King Airs, should they have just shelved the whole idea until they could afford them?
So in the US are they replacing spar caps as per the Piper-approved way of extending wings for another 13,000 hours (-350)? Or just parking them as per original Piper approved method.
Just recently a ndt check was carried out resulting in cracks found in the modified spar. As a result ive been infromed that casa is now looking at the modified spar and talk is now grounding aircraft with this mod.
And I second those that have defended the J2BD, a good engine that is highly intolerant of ignorance. This ignorance was not only the throttle jockeys but also from the heavens of 'approved' sources, refer the Climb Power Leaning Chart in the AFM
100LL won't last forever, no, but I'm pretty sure George Braley has been feeding J2BDs G100UL with fine results!
And comparing PA31 to C208 was done on purpose to try and keep the 'piston twins should be banned' folks at home. A lot of good businesses come from a great idea that then earns money. Not from a lot of money looking for an idea.
RFDS didn't start out with King Airs, should they have just shelved the whole idea until they could afford them?
I've flown J2Bs for 20+ years. I think they're a great engine. But(!)....ignore the aircraft manual's advice to lean at climb power settings. I used to, but now I leave it full rich until after setting cruise MP/RPM.
It wasn't the gippy aero mod, and I can find no one in CASA talking about a grounding
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Hi aeromariner,
Me again! This from a PA31 operator in the US:
Piper said the aircraft is no good after 13,000 hours, how is this operator getting the FAA to ok them out to 40,000 hours? Why can't this be done in Australia? What am I missing!
I'm trying not to be provocative, just would like to know the facts and whether, in hindsight, we got this right in Australia.
Me again! This from a PA31 operator in the US:
We have had a 27,000 and a 39,000 hour plane inspected via eddy current along the holes of this stack and the only thing found was 'indications'.
We send a portion of the latest (39k) one to NAIR for further analysis and are awaiting results.
We currently life-limit these to 40,000 and have two more set to retire (one at 38k and one at 39k). We have yet to find anything significant so will continue on this path.
T
We send a portion of the latest (39k) one to NAIR for further analysis and are awaiting results.
We currently life-limit these to 40,000 and have two more set to retire (one at 38k and one at 39k). We have yet to find anything significant so will continue on this path.
T
I'm trying not to be provocative, just would like to know the facts and whether, in hindsight, we got this right in Australia.
