FAA Maintenance Alert

IAI: 1124-407; Microscopic Holes in Hydraulic Line; ATA 2910
“Approximately 2 minutes after landing gear deployment,” stated a mechanic, “and a few seconds before landing, the flight crew reported an ‘unusual smell’ on the flight deck. No warning or indicator was noted. Landing proceeded as normal. On post flight inspection the hydraulic reservoir was found to be abnormally low. The flight deck was removed and the belly (of this airplane) was (discovered) wet with hydraulic fluid. Visual inspection could not discern the leak area. With pressure applied to the system, a seepage was found in a gear down pressure line, though no visual mechanical defect was noted. After many pressure cycles microscopic perforations in the (hydraulic, gear down) tube at station 96.00 became evident (P/N 723088-171). A repair was made and the aircraft was returned to service.” (Truncating up to five digits off the P/N brings up at least four such leaks in the FAA Service Difficulty Reporting System data base from the same kind of line on IAI aircraft since 1997.) Part Total Time: 10,619.0 hours.  MORE