Emergency Pump - Part 2

This blog covers the plumbing of the emergency hand pump

Overview
The installation of the Cessna style hand pump created a series of problems because of mixing NPT & ISO threads.

Installation

The first issue was the hand pump requiring two 1/8 / 1/4 NPT to M10 x 1.0 custom nipples which were machined from and existing AN6 nipple. 

One  was  was manufactured by machining an M10 adaptor from 16 mm AF 2024-T3 hex bar tapped M10 x 12 deep. Next the AN6 nipple was machined to a OD of 9.08 mm to create a interference fit with the machined hex bar. The other nipple was machined off and the face tapped M10 x 1.0 through. [see photo below]

AN6 nipple machined 
to press fit into adaptor

The hexes on both items we lined up, high strength Loctite applied and the two item pressed together.

Next the Masco Dump Valve had four [4]  Aeroflow NPT to BSP adapters fitted and using a combination of the supplied factory fittings connect both the nylon and braided line.

Hand Pump

Modified AN Nipple
Note: blue is the modified AN nipple

Cutting Braided Hose
The braided hose supplied was cut by wrapping masking tape around the outside and then cut using a sharpened cold chisel. The end was reshaped using flat face pliers then dressed to a smooth finish using a small bench grinder with the tape in position.

Note: FREN TURBO the supplier of the hose dose offer tools for this task

With the tube cut the hole was chased using a 1/8'' rod to ensure the minimum diameter specified by the supplier, finally the braiding was flared using a used pop rivet mandrel to allow fitting of the brass ferrule. Next a ferrule was fitted then tapped with a soft flat hammer onto the end of the nylon tube, finally the nut was position ready to be installed onto the hardware.

Note: The nuts must be fitted immediately after cutting by working the nipplie over the tape with a couple of rotations. The stainless braid is flared exposing the nylon tube with the ferrule tapped on to avoid being pricked by the exposed wire of the braiding.

Before installation each hoses was blown out using compressed air before fitting with all threads treated with Teflon sealant at assembly to secure nuts and provide additional  sealing.

A elbow was selected and fitted to the hose and tighten Next the alignment was checked and if incorrect with the location the assembly was undone, fitting rotated to correct the error. This was repeated until the alignment with the installation point was correct.and the elbow is installed and the nut fully tightened. 

Note:  Once a method for cutting the braided tube was developed it was just time consuming but relatively straightforward.. Never terminate to a straight as uncontrollable twisting is the result. 

Final Assembly

With the hose route finalized all hoses were secured to the air-frame as required using aluminium line separators. All fittings were secured to the side of the wheel well using M3 rivet nuts with pan head screws.  On the underside of the floor they were fitted through aluminium hangers fitted with 'O' rings.

Note: The cut hose was threaded through the openings in the spar before fitting the last coupling.

Finally the dump valve was connected to the manifold using the braided hose and nylon tube all were secured using separator clamps.

Note: Nylon hose is used only on the low pressure side of the circuit.

Comment
Installation worked as planned.