# Delta engine failure two days ago: what's glowing? **URL:** \ **Category:** Factual Questions\ **Created:** [July 10, 2019, 2:29pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834 "2019-07-10T14:29:08Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 10, 2019, 2:29pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/1 "2019-07-10T14:29:08Z")
[A Delta Airlines flight on Monday made an emergency landing after an engine failure](https://www.cnn.com/2019/07/09/us/delta-flight-engine-damage-video/index.html). Passenger video of the failed engine (see link) in the MD-88 showed the turbine spindle’s nose cone, separated from the spindle and being bounced around on the engine inlet grating by the slipstream while the fan blades windmill away behind the grating. Most notable in that video is that the forward end of the spindle, normally hidden by that nose cone, appears to be glowing red-hot. WTF is that? Is that just a spindle bearing that’s failed and is absorbing unholy amounts of mechanical power as the turbine is forced to spin by the slipstream? ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [July 10, 2019, 3:37pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/2 "2019-07-10T15:37:12Z")
I’ll go ahead and give a semi-educated guess until one of the more knowledgeable folks turn up. Behind the nose bullet is supposed to be the accessory dive cover. It’s hard to tell with all the spinning, but I think it’s come off as well. It looks like an exposed No. 1 bearing and N1 tachometer drive gear. The glowing metal is probably the front accessory drive attachment flange. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [July 10, 2019, 3:40pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/3 "2019-07-10T15:40:31Z")
**Bear Nenno** if that’s a semi-educated guess I’d love to see a fully educated one! ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [July 10, 2019, 4:06pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/4 "2019-07-10T16:06:20Z")
> [@Bear\_Nenno](#): > > Behind the nose bullet is supposed to be the accessory dive cover. It’s hard to tell with all the spinning, but I think it’s come off as well. It looks like an exposed No. 1 bearing and N1 tachometer drive gear. The glowing metal is probably the front accessory drive attachment flange. How many serious answers do I have to wait for until I can quote from _Patriot_? ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [July 10, 2019, 4:40pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/5 "2019-07-10T16:40:25Z")
I saw a thread on Reddit that said “…the engine was shutoff at this point. The blades have been spun up by the forward velocity of the plane with the other engine. The bearings are orange hot because of lack of lubrication due to the engine being off yet still rotating.” It’s on the internet, it must be true. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [July 10, 2019, 10:58pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/6 "2019-07-10T22:58:52Z")
> [@Bear\_Nenno](#): > > It’s hard to tell with all the spinning, but I think it’s come off as well. It looks like an exposed No. 1 bearing and N1 tachometer… “Don’t you know? It’s all done with ball bearings these days.” — Gordon Liddy ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [July 11, 2019, 9:03am UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/7 "2019-07-11T09:03:40Z")
> [@Hermitian](#): > > I saw a thread on Reddit that said “…the engine was shutoff at this point. The blades have been spun up by the forward velocity of the plane with the other engine. The bearings are orange hot because of lack of lubrication due to the engine being off yet still rotating.” > > It’s on the internet, it must be true. It may be true, but it’s hard to believe. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [July 11, 2019, 12:26pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/8 "2019-07-11T12:26:06Z")
> [@Melbourne](#): > > It may be true, but it’s hard to believe. Right. Aircraft engines are designed to be fine when turned off. A plane could lose all of its engines at 30,000 feet and glide to safety, all without the engines melting or catching fire, despite the forward movement of the aircraft still causing them to turn. If it’s the No 1 bearing itself that is glowing, then it’s probably from foreign metal debris getting in there. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [July 11, 2019, 1:17pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/9 "2019-07-11T13:17:31Z")
There’s not enough information about this yet to draw conclusions, but that glowing #1 bearing might be the cause of the failure rather than an effect. That is, a disintegrating #1 bearing would heat up as the turbine spins and perhaps stay hot after engine shutdown as the fan gets spun by ram air. Theoretically, such a large thermal gradient could distort the fan spinner hub enough to detach the spinner (as seen in the video). Or maybe the cause/effect arrow points the opposite way and an improperly installed spinner shed debris that ended up being ground up in the #1 bearing, which heated up and disintegrated as a result of that foreign object debris (FOD). That hot bearing could have caused the engine failure or it could be an effect of the engine failure. It’s obviously too early to say which. Bear\_Nenno has more expertise here than I do, just to be clear. But whether the glow comes from the #1 bearing, the accessory drive gear or elsewhere, the glow likely comes froom turning the airflow’s kinetic energy into a fair amount of heat (as Machine Elf postulates). And I agree with others that the Reddit theory doesn’t hold water: a healthy #1 bearing in a shutdown, spinning engine wouldn’t overheat just from spinning while shut down. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [July 14, 2019, 7:46am UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/10 "2019-07-14T07:46:02Z")
> [@Bear\_Nenno](#): > > Right. Aircraft engines are designed to be fine when turned off. A plane could lose all of its engines at 30,000 feet and glide to safety, all without the engines melting or catching fire, despite the forward movement of the aircraft still causing them to turn. If it’s the No 1 bearing itself that is glowing, then it’s probably from foreign metal debris getting in there. [It’s been done](https://en.wikipedia.org/wiki/Gimli_Glider): > [@Wikipedia](#): > > Air Canada Flight 143 was a Canadian scheduled domestic passenger flight between Montreal and Edmonton that ran out of fuel on July 23, 1983, at an altitude of 41,000 feet (12,000 m), midway through the flight. The crew was able to glide the Boeing 767 aircraft safely to an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba, that had been turned into a motor racing track. This unusual aviation incident earned the aircraft the nickname “Gimli Glider”. [And, while we’re on the subject](https://en.wikipedia.org/wiki/Cornfield_Bomber): > [@Wikipedia](#): > > The “Cornfield Bomber” is the nickname given to a Convair F-106 Delta Dart, operated by the 71st Fighter-Interceptor Squadron of the United States Air Force. In 1970, during a training exercise, it made an unpiloted landing in a farmer’s field in Montana, suffering only minor damage, after the pilot had ejected from the aircraft. The aircraft, recovered and repaired, was returned to service, and is currently on display at the National Museum of the United States Air Force. [And the Soviets did it, too](https://en.wikipedia.org/wiki/1989_Belgium_MiG-23_crash): > [@Wikipedia](#): > > On 4 July 1989, a pilotless MiG-23 jet fighter of the Soviet Air Forces crashed into a house in Kortrijk, Belgium, killing one person. The pilot had ejected over an hour earlier near Kołobrzeg, Poland, after experiencing technical problems, but the aircraft continued flying for around 900 km (600 mi) before running out of fuel and descending into the ground. I’d tell you all about the plane that shot itself down, but that would be too far afield. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 15, 2019, 11:39am UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/11 "2019-07-15T11:39:33Z")
> [@Derleth](#): > > [It’s been done](https://en.wikipedia.org/wiki/Gimli_Glider): > > [And, while we’re on the subject](https://en.wikipedia.org/wiki/Cornfield_Bomber): > > [And the Soviets did it, too](https://en.wikipedia.org/wiki/1989_Belgium_MiG-23_crash): > > I’d tell you all about the plane that shot itself down, but that would be too far afield. None of those cases indicated that the engines were healthy and operable after their gliding period. However there is at least one case in which engines were shown to be operable after about 15 minutes of gliding, and that’s [British Airways Flight 9:](https://en.wikipedia.org/wiki/British_Airways_Flight_9) > [@Wikipedia](#): > > On 24 June 1982, the route was flown by the City of Edinburgh, a Boeing 747-200. The aircraft flew into a cloud of volcanic ash thrown up by the eruption of Mount Galunggung (approximately 110 miles (180 km) south-east of Jakarta, Indonesia), resulting in the failure of all four engines. The reason for the failure was not immediately apparent to the crew or air traffic control. The aircraft was diverted to Jakarta in the hope that enough engines could be restarted to allow it to land there. The aircraft glided out of the ash cloud, and all engines were restarted (although one failed again soon after), allowing the aircraft to land safely at the Halim Perdanakusuma Airport in Jakarta. ---
**Author:** ![AHarris](https://avatars.discourse-cdn.com/v4/letter/a/bcef8e/32.png) [@AHarris](https://boards.straightdope.com/u/AHarris)\ **Post date:** [July 16, 2019, 5:01pm UTC](https://boards.straightdope.com/t/delta-engine-failure-two-days-ago-whats-glowing/836834/12 "2019-07-16T17:01:55Z")
> [@Machine\_Elf](#): > > None of those cases indicated that the engines were healthy and operable after their gliding period. The engines didn’t restart in the air (kind of hard without fuel) but the Gimli glider had temporary repairs completed and flew out to a maintenance base 2 days later: > [@Wikipedia](#): > > The aircraft was temporarily repaired at Gimli and flew out two days later to be fully repaired at a maintenance base in Winnipeg.