Riveting of top engine mounts
The engine mounts are rivetted only with the AN5 engine mount bolts and firewall installed. In this situation the mounts are in their correct positions relative to the top rails.
Received replacement RH top engine mount. This mount was replaced as the topside holes misaligned by 0.8mm with the top firewall stiffening channel. I proposed upsizing to 4.8mm to Sling, but they advised against this, preferring to supply a replacement part. This was all bolted into place with the firewall to bring everything into final alignment, then the side rivets installed, with the heads on the inside as the clearance with the rivet gun head is better
The alignment between the top side holes of the mount and the top firewall stiffening channel is much better than previously, with only a need to clean about 0.1-0.2mm misaliignment, down from 0.8mm
Bottom side engine mount holes never posed an alignment problem
4x13mm rivets were used for the bottom outer two rivets. I considered inserting a shim here as a slight gap was evident due to fold tolerances, but this gap was largely pulled closed.
Custom shim shown in position
RH Parachute cable shown bolted in position. The stainless steel brackets had to be bent slightly to make them straighter
Another detail of the LH parachute cable connection.
LH shim edge just visible
LH engine mount shown riveted in position. The topside holes were also found to misalign by about 0.8mm. I did match-drill these holes to match the stiffening channel, but found the 4mm rivet tails would not swell properly into the 0.8mm elongation in the steel brackets. I will be discussing obtaining a replacement from Sling, on the same basis as for the RH engine mount. I am wondering however if the topside rivets - as opposed to the side rivets - are actually much of a structural connection.
This post is from Adam Dickson