Fly Past

90 FLYPAST November 2018

FROM THE WORKSHOP ENGINE RESTORATION

with the propeller and pitch control.
It would have been wrong not to
try to achieve this, as the parts had
essentially stayed together for
41 years.
Although the engine would be
for ground-running alone, I
wanted to restore all parts to
the appropriate standards and
condition, as specified in the
manufacturer manuals.
It was obvious from the outset I
would need to source a significant
number of type- and age-related
components for a fully functioning
engine. This aspect was exciting
and no different from whether you
are restoring a 1926 Royal Enfield
motorcycle or an Avro Anson C.19
engine. It’s a case of continuous
searching and, sometimes,
outstanding luck. Even as-new
items in the original packaging
would be sourced.
In May 2012, I was fortunate to see
the remains of Anson C.19 TX226.
If the undercarriage assembly
could be obtained, could it be
incorporated as a fully functional
system? The exhibit could then
be representative of a complete
engine/undercarriage assembly.
And the paths of TX226 and
G-AGPG were on a metaphorical
collision course.
Approval to purchase the
undercarriage was given and the
assembly was removed in October

2012. The scope of the project was
      complete: a fully functioning Anson
      engine and undercarriage, with
      instrumentation and controls from
      two known aircraft.
      I may be corrected by Avro
      engineers, but I do not believe it
      was ever intended to be able to
      remove the C.19 undercarriage as
      a complete unit. With two friends, I

dismantled the assembly over two

days, but it was far from easy.

Oxidisation battle

Rrestoration of the engine began in

February 2012 and was completed

by October 2013. It was stripped

into its individual components and

each item examined for wear and

damage, dimensionally checked and

overhauled. There was considerable

corrosion on two of the cylinder

bores and associated valve gear.

However, considering the engine

had been stored outside, it was,

internally, in surprisingly good

condition. Because of this the

crankcase, reduction gear box and

auxiliary drive gearbox were not

disturbed; just two replacement

cylinders had to be sourced. But

piston rings, four per piston, were

a different issue. Most of the rings

where badly carbonised and could

not be removed, so replacement

rings had to be sourced. This was

a surprise as the aircraft logs

indicated the engine had only run

for 138 hours of the 600 available

since the engine was reinstalled

following its last service.

Design and development

of the support structure and

trailer continued in parallel. The

complexity of the trailer had been

increased significantly to meet the

aim of running the full propeller

(regarding thrust loading and

ground clearance) and to allow the

undercarriage to raise and lower

fully. The mounting height of the

complete assembly was critical,

not just to meet ground clearance

issues, but also to ensure the trailer

was stable during towing.

The undercarriage mechanism can

only be described as a wonderful

piece of mechanical engineering.

However, in common with the

difficulty of removing it from the

airframe, it was also troublesome

to dismantle and restore to working

condition. Sourcing the missing

parts for the undercarriage, wheel

and axle, was also challenging, but

it was a case of ‘keep looking’ and,

just like buses, two often came

along together.

Good progress

In common with all other aspects

of the project, the aim for the

controls and instrumentation was

to be as authentic as possible.

For the engine, propeller and

undercarriage controls, this was a

straightforward case of restoring

the original G-AGPG equipment.

The instrumentation meets all

the engine and auxiliary services

requirements and is consistent with

type, and fully operational.

The final item for restoration was

the Rotol propeller, and this was

the most challenging but rewarding

part. This prop is the original Rotol

constant speed variable pitch type

R30/242/1 unit fitted to G-AGPG in

June 1958. It was last serviced in

January 1968 and, by the time its

use was discontinued in 1971, just

110 hours of its 1,000-hour life had

been used.

Having spent the last 41 years

outside and moved around the

country, it was in surprisingly

good condition. The chips and

dents on the trailing edges were

all repairable and the hub had only

superficial surface corrosion, but

there was deep corrosion on the

external surfaces of the balance

weight-retaining ring, pre-load and

retaining nut. However, they were

all recoverable and, thankfully,

when completely dismantled

propeller internals were also in

excellent condition.

Without a complete copy of Air

Publication 1538E Rotol External

Cylinder Variable-Pitch Propellers

• Instructions for Repair and
  Reconditioning, this task was a non-
  starter. The tooling requirements
  for the propeller restoration were
  significant, not just for dismantling
  and assembling, but for the
  balancing and setting of the pitch
  angles. All the tools had to be made.

Trial run

On June 12, 2018 the assembly

was rolled out from the workshop

and the propeller fitted along with

the spinner. The restoration was

effectively completed and ready

for towing tests and engine-

running trials.

After a few failed attempts

at starting, the procedure was

changed, and the engine then

jumped into life first time. It runs

very well, starts reliably and the

prime engine parameters, oil

pressure and temperature are

within specification.

The annual Avro Heritage Trust

Air Fair was held at Woodford On

July 7-8, 2018. On the Sunday,

Peter Kosogorin flew the BAE

Systems Heritage Flight Anson,

G-AHKX, providing a beautiful

spectacle. His excellent display

took him directly over the

restored engine of G-AGPG and

the operational undercarriage of

TX226, which performed faultlessly

at its first public display. As a

bonus, inside the Avro Heritage

Museum was the resident cockpit

of G-AGPG, restored to its EKCO

Avionics format. Anson overload?

Probably. But you can never have

too much of a good thing.

Engine restoration complete: the purpose-built
maintenance stand was employed throughout
the rebuild and allowed the engine to be
rotated through 360 degrees.

The undercarriage unit fully dismantled, ready for restoration. Cleaning, inspection and cosmetic

restoration were required before its rebuild.

This rear view shows the original wing rear

spar anchor point for the engine bearer struts,

as well as the mainwheel fork link and the

pilot’s control suite.