During my routine Daily Inspection (DI) on our C42C, I noticed a slight movement of the spinner. It was very slight but enough to warrant investigation. Upon closer inspection, the movement was occurring between the spinner back plate and the hub.
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Not having worked on an E-Prop before, I removed the spinner and attempted to tighten the screws to the required torque. However, two screws didn’t tighten properly, and I feared their captive nuts might have been stripped. I contacted E-Prop support, and I must say, they were very responsive. They promptly sent a service letter EP-SL-002 that predated my C42C’s manufacture date. The service letter detailed the process of removing the prop, drilling out some 4mm holes to 5mm, and fitting higher-quality M5 screws.
The old screws can easily be identified as they are M4 Mushroom head screws while the new ones are M5 Cap head screws, see picture.
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My fear of blind nuts was unfounded as the propeller used nylock nuts within the hub. E-Prop sent me a service pack free of charge. However, this process raised another concern: would I need to reset the prop pitch? Another quick email to E-Prop clarified which screws to remove and which to avoid touching to maintain the propeller pitch.
The next issue was not having a torque wrench that went down to 5Nm, but Amazon came to the rescue here. Not having drilled carbon fibre before, I sought the advice of an expert, who surprisingly advised against using a new drill bit. Instead, they suggested using a worn bit to avoid splintering the carbon fibre.
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With everything I needed, it was time to carry out the required work. It took just over an hour, though I was taking my time and could have done it faster.
First, I ensured the spinner was marked so it would go back on correctly. I removed the spinner screws and the spinner itself, which was straightforward. Setting the spinner aside, I removed the outer retaining prop screws, working my way around and undoing opposite pairs at a time, leaving the top centre one for last. Once all were off, I was amazed at how light the prop was. I set it aside and commenced drilling the holes and replacing the nuts without washers, as per the service letter.
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The process was simple, and reassembly was a straightforward reversal. After completing the work, I logged it in the aircraft’s logbook and took the aircraft for a test flight. Everything was fine, and she is now back in service.
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This experience was a valuable reminder of the importance of thorough inspections and the benefits of responsive support from manufacturers.