Hydraulic Pump Relocation

This blog covers the final relocation of the hydraulic pump and accessories.

Overview
The decision to move the hydraulic pump to the baggage compartment was a matter of convenience and it met the factory request that the COG moves to 18% over the 16% allowable for this model. While it worked, it reduced the size of the compartment but the thought of building a battery mount through the original access hatch was not the first choice.

On the visit to the factory, this was discussed with Franco were it was explained that the relocation of the battery behind the rear of the baggage compartment was an access issue. At this point, Franco showed a new compartment opening that was twice the size now making it possible, the builder returned with a new frame and doubler's to upgrade this aircraft.

Installation
The modification was covered in a previous blog - click here

With the access created the pump/battery was relocated and covered in a previous blog - click here

The final task was to connect the hydraulic lines that were now cut short for the baggage compartment, both plastic return lines were lengthed by trimming in the seat area and adding connectors to reach the new location.

A length of 6 mm od [white] line was purchased but when the connection was tried it would not work but investigation showed that the material selected while dimensional correct it was harder, preventing it from installing correctly. 

A solution was found by heating a T fitting with one of the nipples installed and using it to heat form the flair and this allowed installation to proceed.

The final task was to trim and install the S/S lines on the pressure side and this has been covered previously. The biggest issue is the connections are rigid and can create twisting of the S/S lines, if not done carefully. With the lines installed in the seat area, a nut was fitted and the fitting installed, if found that the alignment was incorrect the nut was re-adjusted, the process repeated until correct the fitting aligned with its location on the pump with the nut nearly fully tight.

The fitting was then tightened and installed using liquid Teflon to seal the threads of the retainer nut.

All lines were secured with aluminium clamps lined with gaffer tape to help reduce chafing in service and secured using M3 S/S cap head screws

The hydraulic pump is mounted on isolators

Center tray is removable to allow access to the cable
and for inspections

Trial fit of all that stuff

Comments
This arrangement created an 18% COG while allowing the lightweight batteries to be retained, as the combined weight of the pump/batteries is equal to the factory battery of 5 kg.

The hose runs are a result of the relocations undertaken and the personal choice of the builder, done again with full access a different run may have evolved, on a positive note this location provides excellent access to the pump and fittings. 

Hydraulic Pump

This blog covers the work to convert the No 2 baggage compartment to a battery / hydraulic compartment.

Overview
The compartment was added in a previous blog along with the relocation of the hydraulic pump and battery.

Why?  - After a series of analyses using the factory cog calculator a 2.5 kg bar was still required at the fin post to achieve a 18.0% minimum cog. This achieved a total weight saving of 1.5 kg over the standard factory battery but I had to live with a bar in the bum - unacceptable.

Current Weight & Balance full tanks 
Empty tanks move the cog to 18.4% MAC

Installation 
The mounts for the battery / hydraulic pump were folded from 0.030'' 2024-T3 sheet into channels. These were mounted to the stringers with 30 x 30 angles folded from the same material and fixed using four [4] four 3.2 mm pop rivets. The channels were then prepared to accept either the battery or the hydraulic pump and then fixed to the angles with 3.2 mm pop rivets.

Fuse link located on the underside to preserve space in the tray
in case I have to use a different battery. Positive and negative studs
are the same as used on the firewall and remove the need to bend the
battery cable through 90 degrees

To preserve access to the inside of the aircraft the center tray was fabricated from 0.5 mm aluminium sheet and fixed to the channels using three [3] M5 screws on each side engaging with rivet nuts fixed into the channels sides and will be used to carry tie downs etc when in service.

Center tray used to store tie downs etc

A set of straps will be added to the center tray to restrain any load placed in that area.


Comment
Very happy with the final location and no it will not move again - promice.

Hydraulic hoses

This blog covers the technique and material used to assembly the hydraulic lines and fittings supplied with the kit. 

Installing Hose Ends

The lines are fabricated from a teflon line covered in a S/S webbing. Cutting this material was is difficult without the factory tool. 

The area to be cut was wrapped tightly in two ]2] layers of masking tape, placed on an aluminium bar then cut with a 25 mm wood chisel and 12 oz hammer. The end is crushed by this operation and is rounded using a pair of flat nose pliers. 

At this point it is critical that the nut be fitted over the hose if the mesh flares just slightly it proved impossible. The nut was rotated over the tape and once fitted the tape was removed. The end was flared using a sharp pick and the nylon dressed square and finally the ferrel was fitted, tapped on using a soft hammer until flush with the end of the tube.

The nut is moved forward then checked that it will rotate freely in its maximum forward position without being fitted.

Brass Ferrule fitted

There is no slippage once the nut is tightened so connecting fittings straight to straight proved impossible.

Straight fittings are fitted first by tightening the nut onto the fitting while allowing the hose to rotate freely, next at the elbow end a dry fitting is conducted. The fitting was wound in by hand until it bottoms, if it did not align with the mounting position the nut was rotated until this was achieved. 

The fitting is now removed with the nut wound back about 270 degrees and the tread coated with a light wipe of liquid teflon from Permintax. The fitting is now install and wound up tight by hand then finally tightened with a 12 mm hydraulic spanner until the fitting aligned with mounting point. 

If it it did not align the fitting was removed and the nut adjusted again and the operation repeated.

Note: The liquid tape was used to prevent galling and assist sealing

The banjo nut was installed and thread coated with liquid teflon, then torqued using a 13 mm spanner until the fitting will not rotate.

Hydraulic Pump Mount

The factory supplied pump has two [2] tapped holes for mounting located on the base. It is a given that the pump will have to be removed at some time, so accessible mounting holes are required.

Factory Installation

Pump Chassis

Flying Legend supplies an aluminium chassis to mount the pump on but when the builder tried to fit it it was found that it would not fit under the control tube and there was no way the safety wire was going to be cut - Plan B.

Plan B
It was decided to create a stand alone chassis for the pump and the attached photos shown the method. A piece 120 mm wide was cut from the factory chassis and reinforced using extruded aluminium angle fixed to the chassis with M3 x 6 pop rivets. 

A set of M5 Rivet nuts were installed to secure the feet of the pump.

A series of lighting holes was added as I felt guilty using 1.5 mm angle and I have the faring tools.

Pump Feet
Two [2] aluminium feet were fabricated from 25 x 25 x 1.5 mm aluminium extrusion. These had to be scalloped to clear the pump motor and reservoir. 

All the M5 screws to mount the brackets to the feet were left from the control installation.

Pump feet installed with M5 s/s cap head screws and spring washers
Note: A larger scallop was required to clear the reservoir
The base mounting holes are clearly seen in this imiage

Finished assembly

Comment: Doing it again the feet would be made at the reservoir side and angle moved to the underside to clear the screws. The feet could have been a flat plate but countersunk screws were required and were not available on the day.