Uncontained Engine Failure South West 737-700

[Quickstatus]

@jb747
Do you remember at what maximum IAS can a pilot safely eject? (understand that even in zero IAS it can be risky)
(Here the poor passenger partially evacuated from the airplane and encountered the slipstream at maybe 800km/h.

This aviator survived an eject at supersonic speeds:

 

[jb747]

800 kph is basically 400 knots. Fast, but you should survive. But, probably on the edge of what is guaranteed. Generally, the slower the better.

The 800 knots mentioned here would normally be considered a case of 'no chance'. He's a member of a very small club. From what I recall though, the first member was a RAF test pilot who ejected from one of our Mirages near Avalon in the early '60s.

You will decelerate very quickly. The Martin Baker seats won't give you a chute if you are over 4G (an indirect way of measuring the speed). A chute at too high a speed is likely to be fatal. So, during the faster part of the journey, strapped into a seat, wearing clothing that is way stronger than anything a normal passenger would be wearing, as well as various harnesses, helmet, mask. At the rate you'd be decelerating, you'd be back below 200 knots in about 2-5 seconds. This poor lady wasn't slowing at all, so it wasn't a few seconds exposure. That small exposure breaks pilots' bodies, and kills many. Her situation is not something that is considered, as it simply isn't survivable.

 

[Bindibuys]

The deceased lady works for the same company as my husband.

 

[moa999]

Cameras exist, including internal ones.

So possibly some internal footage of this incident (or say recent United incidents) not that I'd ever expect such things to ever be publicly released.

But at least enables an actual view of what happened to be seen without the typical witness interpretation.

 

[jb747]

So possibly some internal footage of this incident (or say recent United incidents) not that I'd ever expect such things to ever be publicly released.

But at least enables an actual view of what happened to be seen without the typical witness interpretation.

They aren't targeted at that sort of usage, so I doubt it. And nothing is recorded anyway.

 

[Deleted member 29185]

So with South West suffering another window crack, I wonder if some people are choosing aisle rather than window?

 

[MEL_Traveller]

So with South West suffering another window crack, I wonder if some people are choosing aisle rather than window?

Given the previous incident I think this would have been quite frightening for anyone sitting next to the window or in the vicinity. I know their PR is trying to downplay the issue ('there was never a loss of cabin pressure') - but as a passenger you'd have to be wondering if the crack got that little bit wider the window could blow out.

 

[Quickstatus]

So with South West suffering another window crack, I wonder if some people are choosing aisle rather than window?

Or choosing those “window” seats where there are no windows.

787 have bigger windows

 

[Ansett]

Or choosing those “window” seats where there are no windows.

787 have bigger windows

Yet another reason never to fly on a 787

 

[Quickstatus]

Given the previous incident I think this would have been quite frightening for anyone sitting next to the window or in the vicinity. I know their PR is trying to downplay the issue ('there was never a loss of cabin pressure') - but as a passenger you'd have to be wondering if the crack got that little bit wider the window could blow out.

Nothing happens until it happens!!

 

[straitman]

@jb747
Do you remember at what maximum IAS can a pilot safely eject? (understand that even in zero IAS it can be risky)
(Here the poor passenger partially evacuated from the airplane and encountered the slipstream at maybe 800km/h.

This aviator survived an eject at supersonic speeds:

Here is some information on the supersonic Mirage ejection.

Accident Dassault Mirage IIIO(F) A3-1, 06 Dec 1964

 

[straitman]

A writeup on the engine failure from Aviation Week and Space Technology magazine dated 4th May 2018.

Sean Broderick
Inspections on CFM International CFM56-7B engines since an April 17 accident tied to a fractured fan blade have not revealed a fleet-wide safety issue, and investigators have determined that the engine failure caused a large piece of fan cowl to strike the fuselage and break a window.

NTSB investigators revealed in a May 3 investigative update that the engine failure was contained, with two pieces of the fractured fan blade, in position No. 13, found between the other 23 blades and the outlet guide vanes. It also matched up a recovered piece of fan cowl and latching mechanism with witness marks on the fuselage beneath the broken window.

The NTSB revealed earlier that recovered parts of the blade exhibited cracking. Why the blade cracked, how a contained engine failure could cause the damage exhibited on the Southwest Airlines Boeing 737-700, and how the accident relates to a similar one involving another Southwest 737-700 in August 2016 are likely to be central to the NTSB’s continuing investigation.

• Inspections reveal no widespread issues
• Southwest inspecting all its CFM56-7Bs by mid-May

Both accidents resulted from single fan-blade failures in No. 1 engines. Part of each blade remained attached to the fan hub, and fatigue cracks were found within each blade’s root. Debris caused significant wing and fuselage damage, and each cabin lost pressure.

In the 2016 accident, the aircraft suffered a 5 X 16-in. hole in the fuselage above the wing, though the passenger cabin was not penetrated. One passenger aboard the April accident flight was killed, and the broken window is believed to have been a key factor.

The FAA and the European Aviation Safety Agency (EASA) moved quickly after the April accident, which led to an emergency landing in Philadelphia, to mandate CFM-recommended inspections on high-use CFM56-7B fan blades. CFM’s original recommendations came in a March 2017 service bulletin based on the August 2016 accident, which resulted in an emergency landing in Pensacola, Florida. EASA mandated those checks in March, while the FAA was still finalizing its requirements.

CFM issued new recommendations, and EASA’s April 20 emergency airworthiness directive (AD) superseded the agency’s March order. While the NTSB has not publicly linked the accidents, the moves clearly signal that regulators and CFM consider the underlying issues to be the same.

Similar, damage patterns in the CFM56 accidents have raised concerns. Credit: NTSB
The FAA joined EASA by also issuing an emergency AD on April 20. Regulators ordered ultrasonic inspections of blades on 680 engines with at least 30,000 cycles by May 10. EASA, following CFM’s lead, also required inspections of the remaining 13,300 CFM56-7B engines, all of which power 737NGs, at specific intervals. The FAA on May 2 issued a directive that mirrored EASA’s requirements.

After about 60% of the initial inspections, “no imminent safety concern with the fleet has been uncovered,” says CFM, a GE Aviation/Safran joint venture.

The fan blades on the engine that failed in April had accumulated “more than 32,000 cycles,” the NTSB said in its latest update. They were last overhauled in 2012—10,700 cycles before the accident. The overhaul process included fluorescent penetrant inspections. The blades were lubricated and visually inspected six times between the overhaul and the accident as part of routine maintenance.

“The NTSB materials group is working to estimate the number of cycles associated with fatigue crack initiation and propagation in the No. 13 fan blade and to evaluate the effectiveness of inspection methods used to detect these cracks,” the board said. Following the 2016 accident, a CFM service bulletin added eddy-current inspections into the overhaul process, NTSB added.

Southwest decided after the April 17 accident to fast-track inspections on its entire CFM56-7B fleet—more than 1,400 engines—and finish them by mid-May. As of late April, it had inspected 25,000 of 35,000 blades and reported one anomaly—a cracked blade discovered in 2017.

While attention has focused on the cracked fan blades, the extent of the damage has generated equal concern.

“The loss of the single blade inside [the engine] should not have caused such a dramatic impact,” Southwest Chief Operating Officer Michael Van de Ven said.

Meanwhile, the NTSB has not provided an update on the August 2016 accident since September 2016. The NTSB said the probe “is an ongoing investigation” and that a final report is expected “soon.”

 

[Quickstatus]

Containment ring did its job apparently but cowl departed. Why would cowl not be part of containment ring? Maintenance access?

 

[straitman]

Containment ring did its job apparently but cowl departed. Why would cowl not be part of containment ring? Maintenance access?

The short easy answer is that the containment ring is part of the engine and the cowl is part of the airframe.