Losing An Engine Without Realising: Northwest Flight 5

When you hear about aircraft ‘losing an engine,’ you probably think of the loss being in terms of engine power. But what about when an aircraft physically loses an engine by becoming detached from it altogether? Just such a thing happened to a Northwest Airlines Boeing 727 en route from Miami to Minneapolis, with the incident occurring 32 years ago today.

Northwest Airlines Boeing 727
The Boeing 727 involved was just over 14 years old at the time. Photo: JetPix via Wikimedia Commons

The flight in question

Northwest Airlines flight 5 was a service that originated at Miami International Airport (MIA) in Florida. Its destination was Minnesota’s Minneapolis-Saint Paul International (MSP), the busiest airport in the US Midwest. This is a route plied today by American Airlines, American Eagles, Delta Air Lines, Spirit Airlines (as of tomorrow), and Sun Country Airlines.

Today marks exactly 32 years since a rather eventful iteration of Northwest Airlines flight 5. On January 4th, 1990, the service had 139 passengers and six crew members onboard, making for a total occupancy of 145 people. Operated by a 14-year-old Boeing 727-200 registered as N280US, the flight took off into the Florida skies at around 08:15 local time.

Northwest Airlines Boeing 727
Northwest flew both the -100 and -200 variants of the 727. Photo: Alain Durand via Wikimedia Commons

Unknowingly flying with just two engines

Just under an hour into the flight, something rather peculiar happened. At around 09:10, while cruising over Madison, Florida, the aircraft’s pilots heard a loud bang towards the rear of the plane. Following this, at an altitude of 35,000 feet, AirLive reports that they noted that the trijet’s starboard-mounted engine (on the 727’s right-hand side) had lost power.

Of course, aircraft are designed to still function in the event of a loss of power to an engine. As such, the 727 continued flying under the power of its two remaining turbofans for nearly 50 minutes. However, in the interests of safety, the crew did eventually elect to make an emergency landing in Tampa, Florida. They did so safely at 09:58, with no injuries onboard.

It was at this point that the curious reality of the situation became evident. The aircraft hadn’t just lost power to the starboard-mounted engine, but rather the engine itself! The powerplant was located near Madison a day later, having fallen from the jet inflight.

American Airlines Boeing 727
A similar incident befell an American Airlines Boeing 727 in 1985. Photo: Aero Icarus via Flickr

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An intentional safety feature

An investigation into the incident found that it had been caused by an improperly installed lavatory seal near the engine. This caused the engine in question to ingest frozen fluid chunks inflight, damaging its blades in the process and ultimately causing it to fail. However, the separation of the engine from the aircraft was actually a design feature of the 727.

Indeed, the Chicago Tribune reports that the 727’s turbofans were designed to sheer off ‘under certain conditions.’ This helped keep the aircraft safe, as it ensured a clean break, meaning that the engine didn’t take any of the fuselage with it as it fell. This was also the case in a similar incident involving an American Airlines Boeing 727 in April 1985.

In any case, N280US was able to continue serving Northwest after the incident. According to data from ATDB.aero, it stayed there until 1995, before moving to TransMeridian the following year. It also briefly flew on lease to Aeropostal Alas de Venezuela in 1998.

What do you make of this incident? Did you ever fly on a Northwest Airlines Boeing 727? Let us know your thoughts and experiences in the comments.