NCATT AET case studies
NCATT AET · Put your knowledge to work in context.
The NCATT Aircraft Electronics Technician (AET) certification is a personnel credential for technicians who install, maintain, inspect, and troubleshoot avionics and aircraft electrical systems. ASTM International lists NCATT within its certification programs, and the AET is the foundational level of that family - the entry point on which further NCATT endorsements are built. The NCATT AET case studies are 5 cases and about 3,023 words.
1Chasing a 1.15 V Drop on a Fuel Boost Pump Feeder
A 28 V DC fuel boost pump circuit on a transport-category airplane has a 20 ft feeder run (about 40 ft of conductor, round trip) of 10 AWG wire protected by a 20 A breaker, and the pump draws 20 A. A technician chasing an intermittent low-pressure caution measures 1.15 V from the bus terminal to the pump connector pin with the pump running.
640 words, about 3 min2Adding a Transponder to an Already-Loaded 28 V Circuit
A shop is asked to add a 5 A continuous avionics load (a new transponder) to an existing 28 V DC circuit that already carries a 9 A continuous load. The circuit is 14 AWG wire in a loom with nine other wires, in an equipment bay where ambient reaches 70 C, protected by a 15 A thermal breaker.
586 words, about 3 min3Heading Shows Dashes After a Display Swap
After a display unit is replaced in a two-IRS business jet, the new display shows valid pitch and roll but heading as dashes. The other display, fed from the same ARINC 429 output of IRS 1, shows valid heading.
579 words, about 3 min4A 0.4 Ohm Bond Reading That Should Never Have Been Recorded
During an avionics upgrade, a mechanic must show that a new remote transceiver rack is bonded to primary structure within 2.5 milliohms. Using a handheld DMM on the 200 ohm range with its original test leads, he measures 0.4 ohm between a rack mounting bolt and a nearby structural rib and writes up a bonding failure.
573 words, about 3 min5Substituting Coax and Routing It Past an AC Feeder
An installer is adding a VHF comm antenna to the top of a pressurized fuselage. The approved drawing calls out 18 ft of RG-400 (M17/128) coaxial cable with a TNC connector at the radio end.
645 words, about 3 min