MOD/GYRO/OOl issue
1
Airworthiness Information
Leaflet
Classification: A
Ught
Aarcraft
Associabon
Dragon Wings Rotors
Inspection of Hub Bar
Applicability:
Compliance by:
All LAA Administered Gyroplanes fitted with Dragon Wings Rotors.
1. Visual Inspection: Before each flight.
2. Visual Inspection using xlO Magnification: At the Annual Inspection.
Background:
During a pre-flight inspection the pilot of a Montgomery-Bensen B8
Autogyro noticed a hairline crack in the outside face of the Hub Bar. The
rotor was removed from the aircraft and the blades disassembled from
the rotor. It was found that a crack had propagated from the Hub Bar to
Blade attachment Plate bolt hole significantly reducing the Hub Bar's
strength.
During discussions with the manufacturer of the rotor assembly it was
established that this was the first reported failure of this type and they
suggested that, at some point in the Rotor assembly's history, it had been
incorrectly disassembled/reassembled.
It should be noted that the two (per side) Hub Bar to Blade Attachment
Plate bolts are an interference fit and are not intended to be removed.
Blade removal is carried out by the removal of the blade attachment bolts
(six per side). This procedure must be done in accordance with the
manufacturer's instructions.
Fig. 1. Close up of the Hub Bar showing crack emanating from bolt hole.
Page 1 of 2
Light Aircraft Association, Turweston Aerodrome, Nr. Brackley, Northamptonshire, England NN13 SYD
www.laa.uk.com
Telephone +44 (0)1280 846786
I
MOD/GYRO/DOl
issue 1
Actions Required:
1. Visual Inspection: Before each flight a close visual inspection of the
Hub Bar must be carried out especially in the area shown in Fig. 2..
2. Visual Inspection using xlO Magnification: At each Annual Inspection
the rotor assembly must be removed from the aircraft and the blades
removed from the Hub Bar by removing the six bolts each side in accordance
with manufacturers instructions. After cleaning, visually inspect, using a xlO
magnifying glass, the Hub Bar for cracks. During this check ensure that
there is an appropriate level of lighting. If cracked do not fly the aircraft,
mark the rotor assembly as unserviceable and report findings to LAA
Engineering.
3. If not cracked reassemble Rotor assembly in accordance with
manufacturer's instructions.
Note: Individual blades are 'handed' with respect to the Hub Bar, it is
therefore important to ensure that the blades are refitted in their correct
positions during reassembly.
Hub Bar to Blade Attachment
Plate bolts.
CAUTION: These bolts
must not be removed.
Blade attachment bolt
holes (six per side).
Pre 'hght I",pe~
Area of Concern
Fig. 2. General arrangement of the Dragon Wings Rotor Hub
Certification:
1. Pre Flight Inspection for Hub Bar cracks may be carried out by the pilot.
2. Annual Inspection for Hub Bar cracks must be carried out by a suitably
qualified LAA Inspector. Log book entries must be raised conforming
compliance with LAAjMODjGYROjOOl issue 1
LAA Airworthiness Information Leaflet Classifications
Classification A - Considered Mandatory by the LAA
Classification B - Recommended by the LAA
Classification C - Material published for Information and/or guidance
Page 2 of 2
Light Aircraft Association, Turweston Aerodrome, Nr. Brackley, Northamptonshire,
www.laa.uk.com
Telephone +44 (0)1280846786
England NN13 SYD