Wing De-ice
We recently had a problem with the wing boots failing to fully inflate on a Westwind II. We looked at the distributor valve, all the aft equipment bay plumbing, and the boots themselves for excessive pinholes. All the pressures were within the system limits. We discovered that the wing lines run under the lav floor area, up each side of the fuselage to the wing root bulkhead fittings, and then to the boots. Because the lines under the floor are the lowest point in the system, moisture had collected in them over the years and turned the bottom of the tubes into Swiss cheese. We made new lines, and the system worked perfectly. Next time you are in the area for maintenance, take a good look at the lines, or even put a little pressure in them and do a leak check. It might disclose a similar problem.
Showing posts with label Boot. Show all posts
Showing posts with label Boot. Show all posts
Thursday, March 30, 2006
Friday, September 30, 2005
ATA 30
Surface De-ice Boot Care and Maintenance
Things that could help Westwind operators identify problem areas with the de-ice boots.
Electrical Bonding:
The number one problem I have attributed to premature de-ice boot removal and installation is not neglect – that would be number two on the list – but the lack of electrical bonding. As the Westwind flies very fast through the atmosphere, the de-ice boots will generate static electricity. If the de-ice boot cannot dissipate this static electricity to the airframe, the charge will build up and finally blow out of the de-ice boot leading edge, leaving small cuts in the shape of half circles. Sometimes the damage will be a whole circle if the static electricity is heavy enough. How can this be prevented? First of all, make sure the static dischargers are within limits per the Aircraft Maintenance Manual (AMM) Chapter 23-60-00. The next thing to inspect would be the “DEICER CONDUCTIVE CEMENT” at the trailing edge of the de-ice boots. Without conductive cement, the de-ice boot has no way of discharging static electricity to the airframe. The conductive cement should overlap the de-ice boot and the painted surface. On many occasions I have seen black paint used instead of conductive cement and, of course, the de-ice boots showed severe wear from static discharge.
• Neglect:
“Application of AGEMASTER No. 1 should be made every 150 flight hours” according to AMM Chapter 30-10-00. I prefer Jet Stream PBS Boot Sealant, as it protects against ultraviolet (UV) damage, and it is much easier to remove the old sealant with PBS Prep in order to recondition the de-ice boots. Failure to condition the de-ice boots will cause UV damage and impact erosion, which leaves small pits and holes of irregular shapes along the leading edge. Plus it doesn’t look very pretty. In either case, the de-ice boots will get holes in them and if bad enough, they will not inflate properly, causing a safety-of-flight problem.
Things that could help Westwind operators identify problem areas with the de-ice boots.
Electrical Bonding:
The number one problem I have attributed to premature de-ice boot removal and installation is not neglect – that would be number two on the list – but the lack of electrical bonding. As the Westwind flies very fast through the atmosphere, the de-ice boots will generate static electricity. If the de-ice boot cannot dissipate this static electricity to the airframe, the charge will build up and finally blow out of the de-ice boot leading edge, leaving small cuts in the shape of half circles. Sometimes the damage will be a whole circle if the static electricity is heavy enough. How can this be prevented? First of all, make sure the static dischargers are within limits per the Aircraft Maintenance Manual (AMM) Chapter 23-60-00. The next thing to inspect would be the “DEICER CONDUCTIVE CEMENT” at the trailing edge of the de-ice boots. Without conductive cement, the de-ice boot has no way of discharging static electricity to the airframe. The conductive cement should overlap the de-ice boot and the painted surface. On many occasions I have seen black paint used instead of conductive cement and, of course, the de-ice boots showed severe wear from static discharge.
• Neglect:
“Application of AGEMASTER No. 1 should be made every 150 flight hours” according to AMM Chapter 30-10-00. I prefer Jet Stream PBS Boot Sealant, as it protects against ultraviolet (UV) damage, and it is much easier to remove the old sealant with PBS Prep in order to recondition the de-ice boots. Failure to condition the de-ice boots will cause UV damage and impact erosion, which leaves small pits and holes of irregular shapes along the leading edge. Plus it doesn’t look very pretty. In either case, the de-ice boots will get holes in them and if bad enough, they will not inflate properly, causing a safety-of-flight problem.
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