takair Posted July 11, 2017 Report Share Posted July 11, 2017 Anybody know where I can look at a copy of Lycoming SB 525A? It has to do with mechanical fuel pump LW15473? Depending on which pump you have, there may be a ring on the bottom that is wavy and acts as a spring or a constant compression against the lower diaphragm. Mine seemed like it was too loose. I started tightening but realized this may not be wise and it appears there is an intentional gap under the bolts. In one forum I saw the gap is .03". Apparently 525A calls out the torque. May end up replacing the pump as a precaution anyway if I can't make it right. Relatively low time, but has a few years on it. Can't find much via typical Google search, but I may have the wrong key words. Quote Link to comment Share on other sites More sharing options...
MB65E Posted July 11, 2017 Report Share Posted July 11, 2017 The lycoming site is great, however the search functionI has some improving to do. Yes, those wafers always look loose. I went with a fresh lycoming pump a few years ago. Don't forget carbed and fuel injection pumps have different pressures when you order. -Matt 1 Quote Link to comment Share on other sites More sharing options...
DVA Posted July 11, 2017 Report Share Posted July 11, 2017 This is odd, I can't find it in my Tdata set either. I'll need to research why it's not on the Lycoming site or in my paid subscriptions tomorrow. In the mean time, you'll find it here https://support.cessna.com/custsupt/contacts/pubs/ourpdf.pdf?as_id=22260 included in the Cessna bulletin at the end. 1 Quote Link to comment Share on other sites More sharing options...
takair Posted July 11, 2017 Author Report Share Posted July 11, 2017 4 hours ago, DVA said: This is odd, I can't find it in my Tdata set either. I'll need to research why it's not on the Lycoming site or in my paid subscriptions tomorrow. In the mean time, you'll find it here https://support.cessna.com/custsupt/contacts/pubs/ourpdf.pdf?as_id=22260 included in the Cessna bulletin at the end. Thanks Dave, exactly what I was looking for. As Matt suggested above, the spring ring looks loose. The torque stripe was still in place, but the bolts were not at 30 inch pounds. That said, it is hard to get a torque wrench in place. The SB has two cautions that indicate that the ring should be flat after torque. I know this is to establish orientation, but it also indicates that the spring ring should be compressed. It has been years since I paid attention to one. Do you know if a correctly installed pulsator should have a flat spring ring? Do they end up looking loose as the diaphragm compresses? Should they be occasionally retorqued? It's strange to me that there is no apparent safety feature on any of the hardware. In the attached image you can see the gap between the ring and the lid. (Will need further expert advice on getting the picture oriented correctly) Quote Link to comment Share on other sites More sharing options...
MB65E Posted July 11, 2017 Report Share Posted July 11, 2017 If I had any questions regarding the fuel pump I would just replace it. I don't think there are retorque instructions. I installed the lycoming pump on my engine because of all the AD/SB over the years. I was hoping to have better tracking and reliability. I think Lycoming makes more pumps than tempest and hopefully lasts longer. I couldn't imagine relying on a 25yo diaphragm pump, -Matt 1 Quote Link to comment Share on other sites More sharing options...
takair Posted July 11, 2017 Author Report Share Posted July 11, 2017 33 minutes ago, MB65E said: If I had any questions regarding the fuel pump I would just replace it. I don't think there are retorque instructions. I installed the lycoming pump on my engine because of all the AD/SB over the years. I was hoping to have better tracking and reliability. I think Lycoming makes more pumps than tempest and hopefully lasts longer. I couldn't imagine relying on a 25yo diaphragm pump, -Matt Yeah, I agree, I just ordered a new Lycoming pump. Mine was about 17 years old. Relatively cheap insurance, especially compared to electric pump prices. Price of new was not that much more than repaired, especially once you add shipping charges for the core. I did call Tempest and confirmed a few things. The torque is 30 to 35 inch pounds. The ring is intended to be a locking mechanism for the hardware and provides even compression of the pulsator diaphragm. He said there IS typically a gap at that torque, and if there is not, then it is likely over-torqued. I suspect the Lycoming SB attached is not completely clear with regards to the flatness of the ring. Their intent seems to be with regards to orientation, but it can be misleading. The tech rep at Tempest suggested replacing the pump due to age, but suggested I could verify torque to 30-35 inch pounds if I intended to keep flying it. Not looking forward to swapping it...it's quite buried... 1 Quote Link to comment Share on other sites More sharing options...
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