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On July 2nd a 737-200 departing from Honolulu experienced engine trouble shortly after take-off. The flight ended with the flight crew having to ditch the aircraft and being rescued by the Coast Guard.

Starting at 4:15 in this video the pilot states that the remaining engine is running hot. This is conjecture on my part, but I wonder whether the cause of the engine running hot has something to do with what made the first engine fail.

So my question is: Are there special aspects about the older 737-200 (that may have been fixed in later models of the 737) that could result in both engines failing at around the same time? I have no knowledge about the 737 in general, but an example could be a joint oil reservoir, a pilot action related to the fuel management, or something similar.

Also, related more-so to flight operations: Why would the flight crew choose to fly out over open water instead of returning and landing, or, at least staying closer to the airport?

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    $\begingroup$ Double engine failures that close together are, about 99.99% of the time, fuel related. That's normally the only common denominator. The probability of a system related double failure is beyond one in a billion, the cert requirement. $\endgroup$
    – John K
    Jul 7, 2021 at 0:17
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    $\begingroup$ There can be many causes, and we don’t know for sure until the NTSB report. But in general, when fully redundant systems fail at or around the same time, the most likely cause is a common mode failure. Like the fuel supply, or flying through a flock of geese or volcano ash. $\endgroup$
    – Koyovis
    Jul 7, 2021 at 1:14
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    $\begingroup$ Voting to keep open. There is a methodology in system safety engineering, independent of people's opinion. $\endgroup$
    – Koyovis
    Jul 7, 2021 at 7:56
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    $\begingroup$ At the moment you are asking about a specific accident (Rhodes Express 810), which is still under investigation. Until the final accident report is released by the NTSB, this question is off-topic here. If you want to ask about general reasons, please remove the parts about Rhodes Express 810. $\endgroup$
    – Bianfable
    Jul 7, 2021 at 8:15
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    $\begingroup$ I’m voting to close this question because questions about accidents that are still under investigation are explicitly off-topic as per the help center. $\endgroup$
    – Jörg W Mittag
    Jul 7, 2021 at 8:28

4 Answers 4

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Generally, without knowing the details of this accident, dual engine failures are typically caused by one of the following:

  1. fuel events
  1. ingestion event
  2. flight envelope
  3. maintenance
  4. independent failures; single engine failure followed by:
    • shutdown of the wrong engine (yes, it happened, more than once)
    • over stressing the remaining engine

Regarding the last point (overstressing the remaining engine):

  • If one engine fails, the remaining engine has to provide all the power required to fly.
  • If the aircraft is heavy loaded and flown in demanding atmospheric conditions (hot, humid, high) this may require full power from the remaining engine.
  • Damage to the aircraft external surfaces caused by the initial engine failure may increase drag and thus require additional power from the remaining engine
  • Prolonged operation on full power will stress the engine and increases the risk of failure.

Now looking at the specifics of this accident.

The weather at the airport at the time of the incident was not particularly hot (26 Celsius) or humid (±61 % relative humidity). And being at sea level, the airport is not high either. Note that in case of an inversion layer, the temperature may have been higher at altitude.

The planned flight was approximately 100 NM, so the aircraft was unlikely to be heavy.

Although we can safely reject many of the causes listed above, there is no obvious or very likely cause for this dual engine failure. As always, we have to let the investigation team do their work and wait for the final report.

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    $\begingroup$ +1 for the good reminder in the last sentence. $\endgroup$
    – Ralph J ♦
    Jul 7, 2021 at 17:16
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In general there's a few reasons for a multiple engine failure:

  1. Running out of fuel: This has happened more than once when the wrong fuel load was put on the airplane, see the Gimli Glider and the Azores Glider, there's also a case where hijackers forced an airplane to run out of fuel and ditch because they wanted to flee to Australia
  2. Fuel Contamination: Dirt, water or other contaminants in fuel loaded onto an airplane can cause engine failures. I don't have any good links but there were relatively recently a couple of Cessna Citation jets that crashed or made emergency landings because of contaminated fuel
  3. FOD (Foreign Object Debris): Clouds of birds or ash can cause multiple engine failures. The Miracle on the Hudson is a famous example
  4. Pilot Error: There's been at least one case where a pilot shut the wrong engine down. One engine fails or has a fire and the pilot shut down the working engine. See the Kegworth Air Disaster and Transasia 235
  5. Maintenance errors: Mistakes made in servicing engines can cause failures, for instance using the wrong oil, the wrong quantity of oil, contaminated oil, installing the wrong parts, etc.
  6. Coincidence: It's statistically possible that both engines just broke at the same time, although it's extremely unlikely
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  • $\begingroup$ As two engines approach the end of their service life, it actually becomes more likely that both engines fail within a certain timespan when compared to brand new engines. I believe in this case the second engine was overstressed having to keep the plane in flight alone. The company has a certain rep for its maintenance, if true, that'll pop up as factor in report. $\endgroup$
    – Jpe61
    Jul 9, 2021 at 17:21
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I will not speculate as to the cause of the mishap to which you are referring (Transair 810), however, I believe I can provide some clarity regarding the route over water. The Honolulu airport is located relatively close to Waikiki, a neighborhood with a lot of hotels and apartments. Many airports have noise abatement procedures in place to minimize the impact to residential areas nearby. As it turns out, there is a voluntary noise abatement area off the end of the Reef Runway (26L). This may explain the turn offshore after takeoff. It’s also worth pointing out that ditching (or, god forbid, crashing) offshore is a FAR superior option when compared to the same over a (very densely) populated area. The planned route was to fly the PALAY3 departure, then to the LNY VOR, before flying the CAMPS3 arrival. Obviously, the flight never got beyond the PALAY3. The PALAY3 takes the aircraft initially offshore and away from noise-sensitive areas. enter image description here

A look at the flight path on FlightAware shows the intended route. While it might’ve made more sense to fly a different route, SIDs aren’t customized. They have to serve a variety of routes. The routes work well for ATC flow control and keep aircraft away from risky or noise-sensitive areas and they then disgorge aircraft toward their destinations. Heading offshore isn’t generally dangerous, as twin engine jets are very safe. Hopefully this sheds some light on why the route was picked.

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The oil systems on the two engines are separate, for the obvious reason. If there is (uncontaminated) fuel in the tanks, pilots can't starve the engines without deliberately closing the engine start lever (i.e. shutting the motor down themselves) or getting into unusually nose-high attitudes. The latter don't matter when boost pumps are operating- which is basically always, in flight; nose-high attitude can interfere with gravity-feeding fuel from the main tanks. (But that wouldn't, per se, lead to a "running hot" condition -- rather the opposite.)

Ingesting hail or birds can affect both engines, and can cause damage or failure; damage in the right spot could lead to excessive EGT on the way to engine failure.

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