Gulfstream Fall 2006

• GIV Tail Cone Water Damage
• Airfone Service To Be Discontinued
• Weighing Your Aircraft
• NZ2000 Learning Mode and Full Performance Mode

GIV Tail Cone Water Drainage

— John Kauppila

Duncan Aviation technicians have recently discovered a GIV tail cone with water trapped inside. This particular tail cone, P/N 1159B52901, is typically found on later serial number GIV aircraft. During removal for an inspection, water began to run out from the upper portion of the tail cone. After further inspection, it was determined the water was trapped in the fairing box mounted on the upper surface. This wedge-shaped fairing structure is part of the tail cone, located below the rudder.

The forward portion of the fairing box was removed for access. An inspection revealed the inside to be covered in mold and mildew. Once cleaned, the drain hole was found to be plugged. This drain hole does not exit like the earlier, all aluminum construction tail cones; instead it drains out the aft end of the fairing. Drain holes are located on both sides near the trailing edge of the fairing.

If you have any questions about this topic or any other Gulfstream issue, please contact me by phone at 800.525.2376 ext. 8477.

Airfone Service to be Discontinued

— Dennis DeCook

Verizon Airfone recently announced that it would discontinue air-to-ground phone service in December of 2007. Verizon is encouraging customers to “seek an alternative hardware and service provider who specializes in airborne telecommunications.” Approximately 4,000 aircraft are currently equipped with the MagnaStar system, which will be affected.

Duncan Aviation has developed several solutions for operators who are faced with this disruption of phone service. For more information about options available, contact Dennis DeCook at 800.525.2376 ext. 8418.

Weighing Your Aircraft

— Joe Austin

When weighing your aircraft, please keep in mind that the new weight might be different by several hundred pounds than the previously recorded weight, even though you may not have done any major modifications. The most likely cause is using different scale-s. Even though any scales you use are probably up to date on calibration, differences in manufacturers and allowable tolerance will cause a weight difference. Standard procedure at Duncan Aviation calls for weighing the plane three different times, rotating the load cells to the different jack points, then calculating the average weight for each point. One way to ensure the highest accuracy is to always use the same scales.

NZ2000 Learning Mode and Full Performance Mode

— Jim Wheaton

We’ve been fielding questions lately concerning the Honeywell NZ2000 Flight Management System dropping out of ‘Full Performance Mode’.

Honeywell is familiar with this issue, and recommends that all flight crews operating the NZ2000 system turn off the ‘Learning Mode’ in the NZ2000 after 10 legs or 20 flight hours (whichever represents typical usage) have been recorded in ‘Learning Mode.’ Honeywell also recommends that the FMSs be operated in ‘Dual Mode’ in conjunction with turning off the ‘Learning Mode.’ Doing these two things should alleviate the issue.

If you have any questions about this issue, or any other avionics performance issues, please contact me at 800.525.2376 ext. 8150.

( Return to top )