paul_sherry
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- Aug 16, 2017
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I’ve put this post in the General Discussion area because it’s not specific to a Seneca....
A bit of background - about 4 years ago we bought a low time Seneca V as a kit of parts. It had been involved in a landing accident and, to cut a very long story short, had eventually been disassembled and transported to an aviation engineering storage facility. We bought it ‘in bits’ - fuselage, wings, tailplane, engines, props, undercarriage all separate. We spent a year rebuilding it including having both engines and props field overhauled. Since that rebuild I can’t recall an abandoned flight - until last Tuesday. By the way the engines are TCM TSIO360RB’s - the TSIO360 is very commonly used in Pipers.
Last Tuesday we were moving the aircraft for annual when I got a call from one of my partners to say that the right engine wouldn’t turn over. On pressing the starter it turned over for about 10 secs, then stopped and wouldn’t move again. We suspected a starter motor issue so I went home, picked up a few tools, and headed to the airport where my colleague waited for me. Carefully considering social distancing, we removed the top cover of the R engine and looked at the starter. I have attached an image of the data plate and I guess everyone can work out the problem - especially when I share that all later Seneca’s are 24V electrics.
I can assure everyone that the starter has not been changed since we owned the aircraft and it has clearly worked for the last 3 years.....
Out of curiosity we removed the L cowl and had a look at the data plate on the L starter - definitely 24V.
I sent the picture to our engineers and subsequently called them. Our senior engineer (in whom I have a great deal of trust - we have known them for 15 years) also couldn’t work it out. But, much to my surprise, they had a replacement (24V this time) in stock so after discussion we just got in the car, drove down there - about 2 hours each way - picked up the new one and handed in the old one, and then headed back to refit it. Fortunately a fairly easy job - 2 bolts to hold the main mounting flange and earthing cable and 1 bolt, plus the alt air inlet to remove to facilitate access.
I am astonished that a 12V starter motor, connected to a 24V system, lasted more than about 10 seconds (as opposed to 3 years). Starter motors are very high current devices that get very hot when engaged. Effectively putting twice the rated current through such a device would, I would have thought, cause the windings to burn out in a heartbeat.
I guess it explains why the R engine started so well.........
Why didn’t we notice it before? Well why would you closely inspect a device that seemed to be working fine. The data plate was slightly obscured by the Alt Air inlet pipe so I guess no-one cranked their head around the corner and looked....
At least when it did fail, it failed at home base and we were able to source and fit a replacement within about 4 hours. Fortunately we have engineers that trust us to do fairly easy jobs away from base but I’m sure they will check the install now the aircraft is in for annual.
Paul
Seneca V - G-ZZOT
A bit of background - about 4 years ago we bought a low time Seneca V as a kit of parts. It had been involved in a landing accident and, to cut a very long story short, had eventually been disassembled and transported to an aviation engineering storage facility. We bought it ‘in bits’ - fuselage, wings, tailplane, engines, props, undercarriage all separate. We spent a year rebuilding it including having both engines and props field overhauled. Since that rebuild I can’t recall an abandoned flight - until last Tuesday. By the way the engines are TCM TSIO360RB’s - the TSIO360 is very commonly used in Pipers.
Last Tuesday we were moving the aircraft for annual when I got a call from one of my partners to say that the right engine wouldn’t turn over. On pressing the starter it turned over for about 10 secs, then stopped and wouldn’t move again. We suspected a starter motor issue so I went home, picked up a few tools, and headed to the airport where my colleague waited for me. Carefully considering social distancing, we removed the top cover of the R engine and looked at the starter. I have attached an image of the data plate and I guess everyone can work out the problem - especially when I share that all later Seneca’s are 24V electrics.
I can assure everyone that the starter has not been changed since we owned the aircraft and it has clearly worked for the last 3 years.....
Out of curiosity we removed the L cowl and had a look at the data plate on the L starter - definitely 24V.
I sent the picture to our engineers and subsequently called them. Our senior engineer (in whom I have a great deal of trust - we have known them for 15 years) also couldn’t work it out. But, much to my surprise, they had a replacement (24V this time) in stock so after discussion we just got in the car, drove down there - about 2 hours each way - picked up the new one and handed in the old one, and then headed back to refit it. Fortunately a fairly easy job - 2 bolts to hold the main mounting flange and earthing cable and 1 bolt, plus the alt air inlet to remove to facilitate access.
I am astonished that a 12V starter motor, connected to a 24V system, lasted more than about 10 seconds (as opposed to 3 years). Starter motors are very high current devices that get very hot when engaged. Effectively putting twice the rated current through such a device would, I would have thought, cause the windings to burn out in a heartbeat.
I guess it explains why the R engine started so well.........
Why didn’t we notice it before? Well why would you closely inspect a device that seemed to be working fine. The data plate was slightly obscured by the Alt Air inlet pipe so I guess no-one cranked their head around the corner and looked....
At least when it did fail, it failed at home base and we were able to source and fit a replacement within about 4 hours. Fortunately we have engineers that trust us to do fairly easy jobs away from base but I’m sure they will check the install now the aircraft is in for annual.
Paul
Seneca V - G-ZZOT
