Challenger Spring 2006

• ADC RVSM Interval
• KHF-950 System
• Your Air-Conditioning System

ADC RVSM Interval

- Scott Shefke

Good news for 604 operators! Bombardier is offering relief from the 12-month ADC RVSM interval by incorporating Service Bulletin (SB) 604- 34-052. Be advised of the fine print and check your service bulletin status. You must verify that SB 604-31-003, SB 604-35-001 & SB 604-34-012 have been complied with (SBs 604-31-003 & 604-35-001 should have been complied with to properly have complied with 34-012). Your mod status can be verified by looking at the data plate on the ADC. If it passes per the SB, sign your logs as such and increase your interval, otherwise send the ADCs to Collins for updates.

KHF-950 System

- Kevin Miesbach

Are you experiencing tuning and/or garbled transmitter problems with your KHF-950 system?

Duncan Aviation has seen these issues resolved by installing the following Service Bulletins (SB). Complying with notes in each SB regarding each of the boxes associated with your HF system can keep you from having further problems (such as failure of high-dollar power amplifiers).

KTR-953

• SB 8: To reduce transmit distortion encountered when the KTR-953 is mounted in a different location (> 3 feet) than the KAC-952. KAC-952
• SB 9: To improve common mode rejection encountered when the KAC-952 and the KTR-953 are installed in separate locations.
• SB 10: To reduce transmitter distortion when the KAC-952 is mounted more that three feet from the KTR-953.
• SB 11: To prevent the failure of the power amplifier driver and final transistors.
• SB 13: Mod 13 to improve the tuning reliability of some shunt antennae.
• Ensure these SBs are installed together to avoid further problems.

NOTE: Remember to pull the HF coupler circuit breaker before removing or installing the KAC-952 HF antenna coupler!

Contact Dan Magnus at 800.228.4277 with any questions.

Your Air-Conditioning System

- Scott Shefke

With spring and summer approaching, cabin cooling will become an issue. This is especially true for the crew since conditions in the cabin become quite uncomfortable. When operating correctly, the Challenger cooling system provides a comfortable environment for everyone onboard. Maintenance requirements for the system are rather light; replacing the water sock and visually inspecting the air cycling machine, but many factors can affect the system. These may include proper APU operation, good duct supply pressure, torque of the air turbine, intercooler performance, ACM boots & cabin duct work.

The APU can be a constant source of irritation and poor performance, but we have taken numerous readings of customer’s cooling systems and have found if the duct pressure is at or below 40 psi and the overhead cabin gaspers produce anything less than 3.0 inches of water, there will be complaints. There are some in-field performance checks to help isolate where problems lie and some data we have produced to add the element of empirical data in the analysis of a system.

At your next maintenance event, inspect all ACM boots and duct work, replacing any leaking or deteriorated boots. There is no suggested replacement schedule, but since they are inexpensive, set one of your own. ACM boots are critical in providing the proper air supply for the aircraft pressurization system. If they blow off or rupture, the aircraft’s ability to properly pressurize is diminished.

If you have any question concerning the maintenance of your Challenger, contact Scott Shefke at 800.228.4277 or Skip Thorp at 800.525.2376.

( Return to top )