Discussion Peers Review 2

***This is Aviation Accident investigation Class***

Provide a classmate discussion review /comment addition to what they discussed in their topic discussion 

 

Peers discussion :

Here is my final portfolio artifact regarding the aircraft systems field investigations area. It is an analysis of a near accident (an incident in this case) involving Cape Air, a small airline operator from Massachusetts. 

Cape Air – Continental Connection Flight 9399 Incident Overview

            Continental Connection Flight 9399 was a Part 135 scheduled, domestic passenger flight operated by Cape Air (Hyannis Air Service, Inc.). On January 22, 2009, at about 1828 EST, the flight departed Key West International Airport (EYW) and was enroute to Southwest Florida International Airport (RSW) in Fort Myers, Florida when the aircraft, a Cessna 402C, experienced a total loss of engine power on both the left and right engines (NTSB, 2010).

            The incident flight had been the pilot’s fourth flight of the day. The pilot noted that the first three flights were uneventful. However, he had noticed that from the second to the fourth flight, the difference between the left and right fuel quantities was increasing – with the left tank indicating greater than the right. Prior to departing on the incident flight, the left tank had indicated 300 pounds of fuel while the right indicated 200 pounds. During the aircraft’s climb to 6,000 ft, the pilot noticed a right-wing heavy tendency (NTSB, 2010).

            About halfway through the flight, the pilot positioned the left fuel selector to the right tank position. After 15 minutes, he repositioned the left fuel selector back to the left tank. However, the pilot had actually failed to position and detect that the selector was on its appropriate detent (see Figure 2 below). Thus, both engines from that point were getting their fuel supply from the right main fuel tank only. As the flight progressed, the pilot began to feel concerned about the fuel imbalance, noting that the fuel quantity gauges were indicating 300 pounds on the left and 50 pounds on the right. In the post-accident interview, the pilot stated that he had thought the imbalance was an indication (instrument) issue (NTSB, 2010).       

            A few moments later, the right engine began to quit (the right fuel quantity indicator was indicating zero at this time, while the left was indicating 300 pounds). The pilot immediately switched the right fuel selector to the left tank (crossfeed) which restored engine power. However, the left engine began to surge as well, followed by the right. At this point, the pilot declared an emergency with ATC and immediately headed towards Naples Municipal Airport. He was able to successfully feather both propellers during the approach and landed at Naples uneventfully (NTSB, 2010).

Investigation

            The incident aircraft was secured at a hangar following the emergency landing. It was left untouched until the NTSB investigator arrived. Figure 1 below shows the incident aircraft in the hangar as it was found by the investigators (NTSB, 2009). It can be observed from the photo that both propellers were indeed feathered at the time of landing, supporting the pilot’s account of the event.

Figure 1

Continental Connection Flight 9399 Secured at a hangar in KAPF

            Given the nature of the incident and the information gained from interviewing the pilot, the aircraft’s fuel system was a good place to begin the investigation. The left fuel tank was inspected and found to contain 275 pounds of fuel – matching the reading on the respective fuel quantity gauge. The right tank was likewise inspected and found to contain about 13 gallons of fuel (NTSB, 2010). However, upon checking the flexible fuel lines in both engine compartments, only residual fuel was found in these areas, giving evidence to the total fuel starvation that had caused both engines to fail (NTSB, 2010).

Importance of Cockpit Analytical Techniques

            The fuel starvation had occurred due to the inadequate placement of the left fuel selector on its proper detent. This resulted in the left fuel selector valve (located in the wing) to be between the left and right fuel tank positions (NTSB, 2010). Figure 2 below shows a close-up view of the fuel selectors from the aircraft’s cockpit (NTSB, 2009). Notice here that the left fuel selector was not rotated all the way to the left tank’s proper detent which would have been further to the left (highlighted by the yellow arrowhead). This discovery shows the importance of analyzing and documenting the clues left in the cockpit. As Wood and Sweginnis (2006) note, “in any system investigation, you inevitably work your way down to looking at actual system components” (p, 104). Photographing the system as it was found allows the investigators to keep a record of how it looked like it is examined and tested further (Wood & Sweginnis, 2006). Likewise, if not for this clue left in the cockpit, the investigators may have focused on some other component of the fuel system (such as the fuel selector valves) rather than scrutinizing this component – which eventually yielded a more important finding.

Figure 2

Continental Connection Flight 9399 Fuel Selectors

Time Influence of Accident Findings on Aviation Safety

            Interestingly, during further examination of this particular component, it was discovered that the left fuel tank selector could not physically travel to the proper detent despite efforts from the cockpit because the detents had lacked the appropriate lubrication (NTSB, 2010). The investigators found that Cape Air had not been lubricating the fuel selector detents because they had misinterpreted Cessna’s service recommendations. Though, more intriguingly, when the FAA principal maintenance inspector (PMI) for Cape Air asked other PMIs that had oversight on other Cessna 402 operators, it was found that of the 10 operators in the country, six were unaware that the fuel selector detents had to be lubricated (NTSB, 2010). Accordingly, each of the six operators, along with Cape Air, were immediately required to revise their Approved Aircraft Inspection Program (AAIP) to include the required lubrication of the fuel selector detents (NTSB, 2010).