Service difficulty report · Piston · Dhav DHC6

Difficulty date
June 7, 2013
Submitted
September 14, 2015
Operation
General aviation
Make and model
Dhav DHC6
Part
Piston
Part number
713321
Condition
Damaged
Location
Nlg
Part time
2,500 hours
Stage of operation
IN
How discovered
9
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

(CAN) DURING ROUTINE MAINTENANCE OF A NOSE GEAR PN 71-100-31, SN HS033 SUBASSEMBLY PN 71-300-29, IT WAS DISCOVERED THAT THE FLOATING PISTON ASSY PN 71-332-1 WAS MISSING PARTS OF THE GREEN COATING MATERIAL. SOME OF THE PIECES OF THE MATERIAL WERE LOCATED IN THE HYD FLUID REMOVED FROM THE STRUT. AFTER REVIEWING THE LOSS OF COATING A QUICK EXPERIMENT OF FREEZING THE PISTON TO APPROXIMATELY -50 DEGREES AND THEN LIGHTLY STRIKING IT WITH A HAMMER, REVEALED THE COATING WILL CRACK AND THEN FALL OFF. THE FLOATING PISTON WAS FROM AN ACFT THAT ROUTINELY OPERATES WITH WHEEL SKIS IN THE ANTARCTIC. EXPERIENCE WITH THE NOSE GEAR ASSEMBLIES HAVE SHOWN COATING LOSS ON THE KAMTIC TYPE OF GREEN TYPE OF COATING. THE DACRON BROWN TYPE COATING HAS NOT BEEN SEEN WITH CRACKED OR LOSS OF COATING FROM NORMAL OPERATION. PART TIME AND CYCLES TO BE VERIFIED BY AIRCRAFT OWNER.