RAT’S NEST Bob Lock, Maintenance engineer Gliding Hutt Valley sends us this cautionary tale.
Diaphragm panel damage
A
t the beginning of November I commenced an annual inspection on our ASK 13 trainer. Whilst operating the control column to produce aileron deflection, a scraping / squeaking noise was evident in the starboard wing. Closer inspection revealed serious rat damage to the root rib diaphragm panels and the rib structure at the aileron/brake rod aperture, plus a substantial hole gnawed through the brake box slot rear panel, around the
32
February–April 2017
internal view of the brake box panel
inner brake pivot locking stirrup with one of the two stirrup bolts rendered less effective. More serious investigation was carried out with the use of a CCTV camera on an extending boom, courtesy of our chief tow pilot Tom Clarke, which allowed visual inspection to the outer end of the brake box. The remaining areas were viewed with an endoscope through piercings in the fabric. The results were disturbing.
A rat’s nest was found at the outer end of the brake box containing large amounts of foreign material, including safety notice labels robbed from the cockpit! The fabric at the nest site was severely contaminated and impregnated with urine to the point that the fabric strength had been reduced to almost zero. To add insult to injury, the vermin had destroyed two of the three aileron felt guide bearings and support structure.
