bigflyingrob
5th Sep 2021, 17:01
I fly an Auster with the venerable Gipsy Major fitted with BTH magnetos. Getting these fixed is tricky with Vintech and Deltair charging £2000 a go. i tried a company called Ribblesdale automotive who claim they can fix them.This was returned after 9 weeks at a cost of £390 and I had been forced to source some of the parts as they could not.
The unit failed on first start due to a loose component (known as the points) but I was able to fix this. The engine then ran for 2 flying hours before the magneto failed again. The usual life of a magneto is at least 1000 flying hours.
The unit was returned to Ribblesdale early this year and they sent it back in 3 days saying the points were loose. (again)
On checking the unit I found it no longer provided any sparks when turned slowly which is its principal reason for being. If turned quickly there were reasonable sparks produced but when tried on the engine it was not working correctly.
Reluctant to let them have it again I gave it to a local engineer who is not a magneto expert but is locally recommended.
He found the following faults.
1) The impulse unit had been fitted one hole out of place, so the “TOP” label wasn’t at the top. Resetting this corrected the no sparks problem when in impulse mode.
2) The lock tab holding the impulse mechanism on the shaft was useless, as the tab into the slot for the woodruff key was missing.
3) Several of the 4BA bolts holding the impulse mechanism to the main housing were bent.
4) The brass locating tongue (almost a woodruff key) on the points was useless despite the low grade epoxy that had been used to keep it in the raised position.
5) The engineer fabricated a locking mechanism to prevent further point problems but then when run up on test by using a lathe as a drive source, the magneto would periodically fail.
6) There was brass shrapnel in the rotor probably causing the intermittent failures.
7) After rectifying these faults when tested on the aircraft, the output was insufficient to provide a smooth running engine.
8) The painted marks on the low speed and high speed wheels were in the wrong place causing the distributor timing to be incorrect. As a result the rotor arm was not pointing to the contacts in the distributor cap when the spark was generated.
9) A component known as a condenser mounted on the rotor, was loose.
10) Further investigation showed 2 of the 4 locating pins on the high speed wheel had been filed off. Pictures are of the full speed wheel showing filed pins and two remaining pins. The armature head shows what appears to be 10 holes. However, two are dents due to a past attempt to assemble it when four new holes were drilled. It was a pity two were not in the right place and thus I presume someone took it into their head to file off the misaligning pins. These extra holes would perhaps explain the brass particles found in the rotor. My assumption from this is someone did not realise the 4 pins are deliberately not in a square to ensure correct assembly.
I wrote to Ribblesdale electrics on 20/8/21 asking for their explanation of these facts but as yet have not received a reply.
So has anyone else had problems with them?
The unit failed on first start due to a loose component (known as the points) but I was able to fix this. The engine then ran for 2 flying hours before the magneto failed again. The usual life of a magneto is at least 1000 flying hours.
The unit was returned to Ribblesdale early this year and they sent it back in 3 days saying the points were loose. (again)
On checking the unit I found it no longer provided any sparks when turned slowly which is its principal reason for being. If turned quickly there were reasonable sparks produced but when tried on the engine it was not working correctly.
Reluctant to let them have it again I gave it to a local engineer who is not a magneto expert but is locally recommended.
He found the following faults.
1) The impulse unit had been fitted one hole out of place, so the “TOP” label wasn’t at the top. Resetting this corrected the no sparks problem when in impulse mode.
2) The lock tab holding the impulse mechanism on the shaft was useless, as the tab into the slot for the woodruff key was missing.
3) Several of the 4BA bolts holding the impulse mechanism to the main housing were bent.
4) The brass locating tongue (almost a woodruff key) on the points was useless despite the low grade epoxy that had been used to keep it in the raised position.
5) The engineer fabricated a locking mechanism to prevent further point problems but then when run up on test by using a lathe as a drive source, the magneto would periodically fail.
6) There was brass shrapnel in the rotor probably causing the intermittent failures.
7) After rectifying these faults when tested on the aircraft, the output was insufficient to provide a smooth running engine.
8) The painted marks on the low speed and high speed wheels were in the wrong place causing the distributor timing to be incorrect. As a result the rotor arm was not pointing to the contacts in the distributor cap when the spark was generated.
9) A component known as a condenser mounted on the rotor, was loose.
10) Further investigation showed 2 of the 4 locating pins on the high speed wheel had been filed off. Pictures are of the full speed wheel showing filed pins and two remaining pins. The armature head shows what appears to be 10 holes. However, two are dents due to a past attempt to assemble it when four new holes were drilled. It was a pity two were not in the right place and thus I presume someone took it into their head to file off the misaligning pins. These extra holes would perhaps explain the brass particles found in the rotor. My assumption from this is someone did not realise the 4 pins are deliberately not in a square to ensure correct assembly.
I wrote to Ribblesdale electrics on 20/8/21 asking for their explanation of these facts but as yet have not received a reply.
So has anyone else had problems with them?