Engine Mount Preparation
Both rear pivot faces were dressed on both sides to remove the paint and to ensure that the brass pivot tube projects 0.75 mm [0.030''] nominal beyond the end of the pivot mount ensuring the link will pivot freely with the bolt tightened.
Fitted the limit switch trip to the arm with M4 x 12 pan head screws and spring washers.
Installed the upper pivot arm onto the engine mount after applying grease to the all working faces with the shaft of the bolt coated with Loctite "No Seize" before installation. After the bolt was inserted the exposed thread were wiped with wax & grease remover to remove all lubricant transferred to the thread during assembly, torqued the bolt and rotated the link to confirm free movement.
The main pivot point for the leg consists of a brass top hat bearing and washer fixed with an M10 Grade 8.8 bolt. The area where the brass bearing are installed has a coat of factory paint that was removed. The edge of the area to be not to be cleaned was marked using 20 mm masking tape with the paint removed using a combination of flat files, 240 grit paper and scraping. With the paint removed from both sides the bare steel faces were lightly dressed with a flat file.
The top hat bush was dressed with a file while avoiding damaging the face of the boss, next the washer was polished on a flat surface on 240 grit wet & dry paper. When both were finished the assembly was trial fitted to the pivot point on the undercarriage leg which indicated that the assembly would not rotate freely.
The bolts securing the main pivot were manufactured using a 10 mm grade 8.8 hand threaded to provide the correct bearing area - threads were de-burred and lightly primed, twice with Wattyl single pack etch primer to provide corrosion protection in the thread root.
A suitable 1/4'' drive socket was wrapped in a piece of fresh 240 grit wet & dry paper until it was tight fit in the undercarriage pivot point and rotated squarely through by hand. Once the bush would rotated freely in the hole the pivot point was then de-burred and the assembly re-checked.
The lower pivot point for the lower link was dressed and the bushes inserted to confirm they projected beyond both faces for 0.030'' [0.75 mm] nominal.
Engine Mount Installation
The mount was fitted onto the firewall with the upper link installed as it cannot be fitted after. All mounting bolts were fitted with the aid of a 6 mm drift and 8 ounce hammer. The Nylock nuts were fitted at the inside face with flat washers and torqued to 100 inch pounds.
AN5-26A bolt's were substituted for the factory bolts grade 8.8 bolts requiring two full AN960 washers. A grade 8.8 bolt has a maximum allowable stress of 870 N/mm2 where as a AN bolt has 880 N/mm2 [125000 psi] so they are structurally equivalent but with the AN5 bolt begin 0.002'' smaller in diameter, this was considered by the builder acceptable as the AN bolts allowed a plain shank at each of the load bearing point's between the mount and air-frame.
Nose Gear Mounting
The brass bushes were greased with the pivot points, assembled with the mounting bolts pointing out to create the maximum clearance for the push rods connecting the undercarriage to the rudder for steering. The freedom of the leg was confirmed with it freely oscillating when disturbed. At this point the final link was greased and installed and the operation rechecked - no binds were detected and all bolts torqued to their recommended values.
Hydraulic Cylinder
The cylinder supplied with the kit required each end to be sealed - the top side was treated with Loctite 601 for a permanent assembly and the lower with Loctite 232 [Teflon tape is used by the factory]. The position of the two inlets was aligned to allow the hydraulic hose's to be connected at the front or the cylinder.
To mount the cylinder brass top hat bushes were inserted into the mounting holes with the factory bolts fitted and torqued top and bottom. The ports for the cylinder were covered with masking tape with a small hole pricked allowing the cylinder to breath during assembly and hand cycling.
All bolts are marked with yellow paint to confirm that all bolts are now torqued.
All in all no real issues encountered - a good few days.
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| Upper Pivot Mount Dressed |
Fitted the limit switch trip to the arm with M4 x 12 pan head screws and spring washers.
Installed the upper pivot arm onto the engine mount after applying grease to the all working faces with the shaft of the bolt coated with Loctite "No Seize" before installation. After the bolt was inserted the exposed thread were wiped with wax & grease remover to remove all lubricant transferred to the thread during assembly, torqued the bolt and rotated the link to confirm free movement.
 |
| Upper Pivot Installed This pivot must be installed before fitting engine mount |
The main pivot point for the leg consists of a brass top hat bearing and washer fixed with an M10 Grade 8.8 bolt. The area where the brass bearing are installed has a coat of factory paint that was removed. The edge of the area to be not to be cleaned was marked using 20 mm masking tape with the paint removed using a combination of flat files, 240 grit paper and scraping. With the paint removed from both sides the bare steel faces were lightly dressed with a flat file.
The top hat bush was dressed with a file while avoiding damaging the face of the boss, next the washer was polished on a flat surface on 240 grit wet & dry paper. When both were finished the assembly was trial fitted to the pivot point on the undercarriage leg which indicated that the assembly would not rotate freely.
The bolts securing the main pivot were manufactured using a 10 mm grade 8.8 hand threaded to provide the correct bearing area - threads were de-burred and lightly primed, twice with Wattyl single pack etch primer to provide corrosion protection in the thread root.
 |
| Main Gear Pivot - typical both sides |
A suitable 1/4'' drive socket was wrapped in a piece of fresh 240 grit wet & dry paper until it was tight fit in the undercarriage pivot point and rotated squarely through by hand. Once the bush would rotated freely in the hole the pivot point was then de-burred and the assembly re-checked.
The lower pivot point for the lower link was dressed and the bushes inserted to confirm they projected beyond both faces for 0.030'' [0.75 mm] nominal.
 |
| Nose Gear Lower Link Attach Point |
Engine Mount Installation
The mount was fitted onto the firewall with the upper link installed as it cannot be fitted after. All mounting bolts were fitted with the aid of a 6 mm drift and 8 ounce hammer. The Nylock nuts were fitted at the inside face with flat washers and torqued to 100 inch pounds.
AN5-26A bolt's were substituted for the factory bolts grade 8.8 bolts requiring two full AN960 washers. A grade 8.8 bolt has a maximum allowable stress of 870 N/mm2 where as a AN bolt has 880 N/mm2 [125000 psi] so they are structurally equivalent but with the AN5 bolt begin 0.002'' smaller in diameter, this was considered by the builder acceptable as the AN bolts allowed a plain shank at each of the load bearing point's between the mount and air-frame.
Nose Gear Mounting
The brass bushes were greased with the pivot points, assembled with the mounting bolts pointing out to create the maximum clearance for the push rods connecting the undercarriage to the rudder for steering. The freedom of the leg was confirmed with it freely oscillating when disturbed. At this point the final link was greased and installed and the operation rechecked - no binds were detected and all bolts torqued to their recommended values.
Hydraulic Cylinder
The cylinder supplied with the kit required each end to be sealed - the top side was treated with Loctite 601 for a permanent assembly and the lower with Loctite 232 [Teflon tape is used by the factory]. The position of the two inlets was aligned to allow the hydraulic hose's to be connected at the front or the cylinder.
To mount the cylinder brass top hat bushes were inserted into the mounting holes with the factory bolts fitted and torqued top and bottom. The ports for the cylinder were covered with masking tape with a small hole pricked allowing the cylinder to breath during assembly and hand cycling.
All bolts are marked with yellow paint to confirm that all bolts are now torqued.
All in all no real issues encountered - a good few days.
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