The start-up goes as expected. Blades are turning, we’ve completed the pre-takeoff checks, the gauges are all in the green with warning lights extinguished. We pull pitch, gently lifting the helicopter into the air, and perform our hover check. All is well and we continue the takeoff. Still climbing, we glance at the gauges and see the engine oil temperature needle moving from the green toward the red limitation line. The needle crosses into the red—the engine oil temperature is now over the limit.
The emergency procedure (EP) includes landing as soon as possible, but we’ve also been having problems with this gauge in the past and maintenance personnel replaced it multiple times as part of their troubleshooting. Do we follow the EP? Is this just another gauge problem? If we think it is just another gauge problem, should we continue the flight and see what happens?
Follow the Emergency Procedure
On January 23, 2015, a United States Marine Corps (USMC) UH-1Y Venom crashed near Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, after the main rotor transmission seized from a complete loss of oil during a squadron exercise. The actual mechanical issue that caused the crash was an improperly installed transmission oil filter cover, which resulted in the dumping of virtually all of the oil in the main rotor transmission and its subsequent seizure.1
However, there is one important event in this fatal accident that all pilots should take note of: “About 34 minutes into the 49-minute flight, the pilots noticed that their oil pressure gauge fluctuated and then plummeted to zero.”1 While the EP included the task of “Land As Soon As Possible”, the pilots continued to fly the aircraft an additional 15 minutes after the indication of a loss of oil pressure, despite the availability of numerous landing sites in that area, to include two actual airports that they passed by just prior to the seizure of the transmission. If you’ve ever been there, as I have for pre-deployment training during my Marine Corps career, it’s basically a desert with mountains and tons of simple off-airport landing sites.
Why did they continue flight instead of make an immediate landing?
The report speculated that “the pilots likely assumed the problem was due to a faulty gauge, not actual fluid loss, because of recent maintenance issues”, as approximately “a week prior, their aircraft had undergone maintenance because of a faulty reading, which included replacing oil pressure sensors”, and the pilots “calmly called to have avionics troubleshooters standing by on the flight line.”1
A false indication of an emergency is often referred to as a nuisance alarm. While the first occurrence of such an event will likely result in our proper response to the associated emergency, repeated nuisance alarms for the same issue may encourage us to ignore or delay our response—often called alarm fatigue—assuming it is just a repeat of the same non-emergency issue, such as a faulty gauge or sensor repeating an error despite various attempts by maintenance to resolve the issue. We’ve probably all seen at least one of these nuisance alarms in our flight careers, and the situation I started this article with is one with which I was presented in a specific base’s helicopter that I didn’t normally fly in.
The fatal accident at Twentynine Palms is an unfortunate example of allowing complacency to impact decision-making in critical issues. We can completely see why the crew would have felt that the alarm was a nuisance alarm based upon the prior maintenance and documented issues with the oil filter on that specific ship, but we as pilots have to remember that there is always the possibility that even a nuisance alarm is real, and we should treat each as such by following the specified procedure. If they had followed the procedure, they would likely be alive today.
Combined with the general complacency that can develop from nuisance alarms, we also are exposed to a stronger case of the “get-there-itis.” None of us like to be stuck somewhere waiting for maintenance, and we are susceptible to stretching an immediate landing to a more “practical” landing when encountering such alarms. As hard as it is, we have to accept that our jobs as pilots means that we can get stuck somewhere at any given moment. Don’t cave to the pressure of getting back home on time and stretch an issue.
Follow the emergency procedure.
The Importance of Understanding Our Aircraft’s Systems
Now, this does not mean that you should skip troubleshooting a non-immediate issue for a solution, as there is always the possibility that you self-induced the alarm/indication. For example, one could accidently trip a hydraulic switch while moving about in the cockpit: you wouldn’t immediately execute a running landing without checking the switch or other controls first, right? The same goes for other issues that you may have some control over or other instruments available to cross-check the situation, which illustrates another key point: know your aircraft’s systems.
In my opinion, one of the weakest sections of many common Rotorcraft Flight Manuals (RFM) is the Systems Description. While much of the information provided is very useful, sometimes they describe a system with too much detail that isn’t impactful for pilot decision-making, and other times they completely skip over information that would be good to know. For example, I’ve seen one aircraft’s RFM have a thorough description of every system on every electrical circuit, so you would know what systems are impacted depending on the failure/switch/fuse/circuit breaker configuration at a given time, but ignore telling us about related Full Authority Digital Engine Control (FADEC) faults and their solutions/causes with external power applied, which is a common operating situation in cold environments.
It’s a good idea to get as familiar as we can with the systems information in the RFM, but then to supplement that information with a review of the maintenance manual, additional airframe training resources available, talking with our mechanics, and even reading incident/accident reports involving that airframe. I’ve probably learned more from talking and following along with mechanics during normal maintenance than most other sources, and this information has helped me in situations troubleshooting in the air and on the ground.
I posted a photo on Instagram not too long ago asking what pilots thought they should do if all of the lights on the Caution Warning Panel (CWP) illuminated in-flight, as I know someone that this happened to. That pilot did the right thing: he reasonably thought that the issue was with the CWP itself, as it was unlikely that all system failures represented occurred at the same time. So, he troubleshot the CWP by manipulating the CWP Test switch, with no resolution. Since that fix didn’t work, even though it was reasonable to assume that the issue was with the CWP itself, he elected to land in the nearest safe spot—a large field, in this case.
Why was this a good idea?
Because now that the CWP was stuck fully illuminated, he couldn’t determine if either a system failed simultaneously with the CWP or if one would fail while continuing flight to the destination. He had to deal with the inconvenience of being in a field for a few hours, but he and the passengers were safe.
Yes, I immediately landed the helicopter from the introductory situation on the airfield at the nearest safe spot, and got maintenance dispatched despite the troubleshooting history of the gauge. In the decision-making process, I certainly considered that it was likely just a gauge issue, also noting no additional problems indicated by other gauges, but I stuck to the principle I had set for myself early on in my career: Every emergency is an emergency.
Study those systems,
- Marine Corps Times. (October 25, 2015). Investigation: Faulty filter cover, pilot error caused fatal Marine helicopter crash. Retrieved January 2, 2018 from https://www.marinecorpstimes.com/news/your-marine-corps/2015/10/25/investigation-faulty-filter-cover-pilot-error-caused-fatal-marine-helicopter-crash