FAA moves on the engine corrosion that crashed a Challenger on I-75

Airworthiness Directives (ADs) are the FAA's mechanism for forcing fixes to unsafe conditions across an aircraft or engine line. They cover models or entire fleets of aircraft that could experience the same issue. These ADs typically have comment periods for the public to provide feedback. The comment period for the latest FAA proposed AD on certain General Electric Company engines ended on June 15. It reports that the engines could have corrosion that can lead to engine shutdown. The crash that triggered the directive The AD was triggered by a Bombardier Challenger 604 that crashed on a Florida interstate on Feb. 9, 2024. While the aircraft was attempting to land, it received three master warnings about engine oil pressure. Less than a minute later, the crew announced they had lost both engines and would not be able to make the runway. The jet then crashed onto Interstate 75 and burst into flames, killing 50-year-old pilot Edward Daniel Murphy and 65-year-old copilot Ian Hofmann. Attendant Sydney Ann Bosmans, 27, coordinated the successful escape of passengers 35-year-old Aaron Baker and 23-year-old Audra Green, as well as herself, through the baggage compartment door in the tail section of the aircraft. The NTSB also reports that one person on the ground sustained a minor injury. The NTSB later found that the 604's compressor case and variable geometry (VG) system hardware had corroded steel and elements typically found in a marine environment. The jet was mainly stored in airports that were close to the ocean, and the corrosion likely built up over time. The operator reported that it has experienced multiple hung starts in the past decade, including one that was 25 days before the accident. These hung starts are an indicator of corrosion build-up, which could have been identified through an MP 68 pressure check. This step was very late in the fault-isolation hung-start guidance and was not a required maintenance check as the engines managed to restart, so the corrosion remained undetected. The NTSB stated that the corrosion of the VG system resulted in both engines failing and the Bombardier Challenger 604 crashing. It also stated that inadequate fault-isolation guidance from the engine manufacturer prevented the identification of corrosion buildup in the aircraft during troubleshooting. As a result, the engine manufacturer published an updated version. What operators would have to check The corrosion affects GE Model CF34-1A, CF34-3A, CF34-3A1, CF34-3A2 and CF34-3B engines, according to the FAA. The proposed AD requires performing repetitive engine heat soak restart tests for a hung start and, depending on the results of the tests, engine troubleshooting and corrective actions. It also requires operators to perform a borescope inspection (BSI) of the HPC case for corrosion, a force gauge test on the feedback cable for tightness, a visual inspection of the VG system for obstruction and revise the Airworthiness Limitations Section (ALS) of the existing engine maintenance manual to incorporate the VG system functional check. Depending on the results of the tests, performing a VG system functional check for pressure evaluation or even removing the engine from service. Market Impact For buyers, you will need to ask if the aircraft was operated in a coastal or salt-heavy environment and check to see if the engine records show any borescope corrosion findings or related VG service-bulletin work. A pre-buy inspection will need to go check the engines to ensure any corrosion has not gone undetected. For sellers and brokers, documentation will be their best friend if this rule becomes final as aircraft with clean, dated VG-system inspection records will clear the market. Aircraft with undocumented engine histories will see deals drop and a decrease in value. For those who already own aircraft with these engines, they should start budgeting for inspections, teardown and extended downtime if the corrosion builds up. It is important to price the inspections now, before the final ruling, especially with aircraft based on the coast. While this AD is still just a proposal, the market is already pricing it. Owners and sellers who make the move now to inspect and document their engines will be the ones who will not have to scramble to meet its requirements and face major downtime.