FAA, NTSB Not Clear About Pilatus Chip Detector Based on its review of engine failure events on the Pilatus PC-12 single-engine turboprop aircraft, the National Transportation Safety Board (NTSB) wants alerts of oil contaminated by metal particles to function during all phases of flight.

The engine's oil system features a magnetic chip detector (MCD), which monitors the oil scavenged from the reduction gearbox connecting the engine to the propeller. Pieces of metal from internal wear or damage in the gearbox circulating in the oil are attracted to a magnetic chip detector (MCD). When sufficient material collects, an electrical circuit is completed between the two poles of the MCD and a warning is displayed on the airplane's central advisory and warning system (CAWS) in the cockpit.

The NTSB said in its January 7 letter to the FAA, "The CAWS receives a signal from the weight-on-wheels (WOW) switch on the left main landing gear. As soon as the airplane takes off and the WOW switch is opened, warnings are disabled.

"The Safety Board is concerned that having the MCD warnings disabled in flight negates the purpose of the system - to warn the flight crew of potential problems," the NTSB letter said.

The very next paragraph of the NTSB's letter speaks volumes about the difference between proactive and passive safety cultures: "The Safety Board notes that when PC-12 and PC-12/45 airplanes were registered in Canada, Transport Canada required that they be modified so that the installed CAWS would display any engine MCD warnings throughout all phases of flight. Pilatus issued Service Bulletin No. 04-002 [meeting this mandate] ... When PC-12 and PC-12/45 airplanes were registered in the United States, the FAA did not impose a similar requirement." The lack of said requirement is now the subject of the NTSB's attention. For full text of the NTSB letter, see www.ntsb.gov/recs/letters/2004/A03_58_61.pdf.

Update: A mandatory Service Bulletin was issued by Pilatus in February for the installation of a magnetic chip detector that would be functional in all phases of flight for the serial number aircraft in question. Just prior to publication of this magazine, on March 30, 2004, the FAA followed up by publishing a special airworthiness information bulletin (SAIB) recommending the installation as soon as possible. In this FAA bulletin, the installation is not required. This does not seem to quite meet the object of the NTSB recommendation. Note: This news was provided by AM sister publication Air Safety Week. For more information about ASW visit www.aviationtoday.com.