Another modification I am making in the firewall area of my RV-10 is upgrading to a larger oil cooler (
Airflow Systems 2007X vs. the recommended 2006X). Running SDS EFI and cold air induction on my engine, along with my home base being in warmer climates within CA, I wanted to ensure that I have adequate cooling available as needed.
The downside of this is that the 2007X oil cooler is taller than the 2006X cooler (due to an additional 2 rows of cooling fins). It therefore won't fit the stock Van's cooler mount as is, and I need to modify the mounting bracket to accommodate the bolt locations on the larger oil cooler. This modification has been done by numerous other builders, and mine is no different.
The lower bolt holes on the stock mount remain where they are. In order to space the top and bottom bolts further apart I have to remove the top row of predrilled bolt holes, and drill new bolt holes into a piece of 1/16" thick angle that will be attached to the top of the mount.
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| 3/4"x3/4"x1/16" angle cut to width and held in place where it will eventually be attached to the oil cooler mount. The angle interferes with the air duct flange, so needs a little trimming in that area (marked with sharpie)) |
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| After trimming, the angle is aligned with the edge of the oil cooler bracket and fits nicely around the flange. Here you can also see the TCW 4" butterfly valve placed over the flange. I had to make sure to trim the angle enough to accommodate the butterfly valve |
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| I then drilled 1/8" (#30) rivet holes into the angle for attachment to the oil cooler mount, ensuring I had adequate edge distance, especially around the trimmed portion |
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| Angle clamped in place on the oil cooler mount, and rivet holes match drilled into the mount |
Next I carefully trimmed away the portion of the mount where the top row of bolt holes / nutplates were located
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| Portion to be cut away was marked, and holes were drilled near the corners to make trimming easier |
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| Corner holes were enlarged using the step drill up to the cutout lines |
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| Flange was then cut away using a cutoff wheel in the Dremel |
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| After cleaning up the rough cut edges, I clecoed the angle on to the mount and with the oil cooler held in place marked the new locations of the bolt attachment holes onto the angle |
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| Oil cooler placed over mount showing where bolts will attach through the fabricated angle |
With the bolt hole locations marked on the angle, I drilled each hole to #10, and used a #10 nutplate jig to drill nutplate attach holes at the required spacing.
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| Angle clamped to workbench while I drill bolt and nutplate holes |
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| Nutplate attach holes were countersunk for an AN426-3 rivet |
When using the larger oil cooler, Airflow Systems also recommends installing a vane within the oil cooler mount to direct airflow evenly over the cooler fins. Instructions to fabricate this mount are clearly documented, so I just followed those to finish out this modification.
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| Location of internal vane marked on the exterior of the oil cooler mount. The vane needs to be bent at the location shown so that it splits the airflow roughly in half |
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| After fabricating the vane from 0.040" aluminum, I used the vise to impart the bend at the required location |
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| Bend started slowly by hand... |
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| ... but then became easier as the angle increased. I removed the vane from the vise a couple of times to check the bend angle and was able to finesse it to match the vane positioning marked earlier |
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| Vane deburred and bent. I also cut out some 1/16"x3/4"x3/4" angle pieces that will be used to support the vane within the oil cooler mount |
I then drilled mounting holes into the vane support angles and match drilled those to the oil cooler mount.
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| After drilling mounting holes into the support angles, I placed the vane into the oil cooler mount and clamped the angles in place. I was then able to use my angle drill to match drill the mounting holes into the oil cooler mount... |
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| ... and then into the vane itself. These were all sized for a 3/32" (#40) rivet. |
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| Vane and support angles drilled and deburred |
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The final step before riveting involved countersinking the holes in the vane supports and dimpling #40 holes in the oil cooler mount and vane. To countersink the narrow supports, I clamped them between the longer supports for added stability
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With all modification to the oil cooler mount complete, I was then ready to start riveting the pieces together.
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| The pneumatic squeezer was used to rivet the support angle to the airflow vane, making sure the narrower angles were positioned correctly to fit flush against the oil cooler mount side walls |
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| Top angle attachment rivets were bucked |
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| The vane was attached to the oil cooler mount sidewalls, and K1000-3 nutplates were also attached. I used the squeezer for all rivets here, but had to be somewhat careful riveting nutplates around the duct flange due to limited clearance. I used the Main Squeeze hand squeezer where space was very limited as it gave me better control while riveting |
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| Oil cooler mount modifications complete! Seen from the top... |
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| ... right side... |
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| ... left side... |
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| ...and inside! |
Time Taken: 7.9 hours
Dates: May 8 2025 - May 18 2025
Firewall Total Time: 35.2 hours
RV-10 Build Total Time: 1022.1 hours
Priming Total Time: 126.0 hours (not included in build time totals)
