Page 40 - Volume 13 Number 9

the release states that it cannot be loaded into the 9000000-85006 part number unit. The TAWS system will continue to operate normally on the last database loaded, however obstacles and airport data would not be up to date in the unit. TACSS released optional service bulletin (SB) 9000000-34-6037 to upgrade the memory in fielded units from 128MB to 256MB and converts the unit to part number 9000000-85010. Textron approved the upgraded unit as a spares replacement allowing fielded aircraft to upgrade their units through ACSS and reinstall the new part number without the need of an additional kit or other approval. The spares notes should be added to the related model illustrated parts catalogs as future revisions are released. In the interim, we have placed technical manual deviation approvals (TMDAs) in 1View to provide the approval documentation. The TMDAs can be accessed by going to the IPC section detailing the TAWS computer and clicking on the TMDA tab at the top of the screen, see illustration above. Please contact your local service center in advance for a quote
and to coordinate the upgrade as the unit will have to be sent to ACSS for modification. The SB requests a minimum two-week lead time to schedule units in for modification to avoid delays getting the unit returned.
The computer was factory installed in the aircraft listed below:
LJ-1847 and LJ-1853 to LJ-2128; BB-2001 and after; BY-42 and BY-58 to BY-276; BZ-1; FL-600 to FL-611, FL- 613 to FL-617 and FL-619 to FL-1080; FM-25 to FM 70.
ATA-77 Collins Pro Line 21 and Pro Line Fusion Fuel Flow Indication
All
There have been sporadic reports of the electronic engine indication system (EIS) fuel flow readings dashing out (Pro Line 21) or showing XXX (Pro Line Fusion) a few minutes after engine start but returning to normal as the aircraft climbs to colder temperatures.
The common conditions for these reports were ramp temperatures are above 32° C (90° F), and the cause was traced back to a stuck thermal element in the oil to fuel heater.
When this element sticks in the open position, it allows oil to continually heat the fuel. The fuel flow transmitter receives fuel temperature as an input and uses it for compensation in the resulting fuel flow signal. If the fuel temperature exceeds approximately 70° C, the fuel flow transmitter will consider the input to be invalid, triggering the dashes or Xs on the display.
To isolate a stuck thermal element, both engines can be run until the fault occurs then shut down. An infrared thermometer can then be used to check the fuel line temperature at the outlet of the fuel heater or the inlet to the fuel flow transmitter. Comparing left and right temperature readings will compensate for local conditions. A temperature split of as much as 20° C will indicate a stuck thermal unit. This condition was not seen on legacy analog systems as they did not monitor the validity of the temperature compensation from the transmitter.
The information provided in this column may be abbreviated for space purposes. For the entire communication, go to www.txtavsupport.com.
SEPTEMBER 2019
38 • KING AIR MAGAZINE