Iceland B752 at Keflavik on Feb 7th 2020, main gear collapse on landing

Last Update: April 6, 2020 / 22:43:13 GMT/Zulu time

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Incident Facts

Date of incident
Feb 7, 2020

Classification
Accident

Airline
Icelandair

Flight number
FI-529

Aircraft Registration
TF-FIA

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

An Icelandair Boeing 757-200, registration TF-FIA performing flight FI-529 from Berlin Tegel (Germany) to Keflavik (Iceland) with 160 passengers and 6 crew, landed on Keflavik's runway 10 at 15:46L (15:46Z) but suffered the collapse of the right main gear. The aircraft came to a stop on the runway resting on its nose gear, left main gear and right engine. The passengers disembarked onto the runway and were taken to the terminal. There were no injuries.

Passengers reported the aircraft bounced on landing, on second touchdown the right main gear collapsed and the aircraft skidded on the engine releasing sparks and smoke from the engine.

A passenger video off the left hand windows shows the aircraft touched down smoothly, the spoilers deployed, the aircraft bounced slightly (probably without the wheels becoming airborne again), smoothly came down a second time, then the right main gear collapsed and the spoilers retracted. Another passenger video, only available in time lapse so far, off the right hand windows shows the aircraft touched down smoothly, the right wing may have lifted a bit, the right main gear possibly became airborne for a bit, touched down again smoothly and the aircraft sank further on its right main engine now with sparks coming off the engine cowl (editor's note: user Ruan/Ruan60989131, if you read this, we'd be interested in the full normal time video including approach and roll/skid out, please contact me via the contact form below).

On Feb 8th 2020 The Aviation Herald received information that the gear of the aircraft had been replaced mid January 2020. There was no damage to the right main gear, however, a bolt holding the gear mechanism together was missing (see photo below).

On Feb 10th 2020 Iceland's RNSA (accident investigation) reported the missing parts from the landing gear have been found on the runway. The gear was new, having been installed on the airframe between Nov 19th 2019 and Jan 6th 2020 and had done several sectors since. The US NTSB (state of manufacture) and Canada's TSB (state of maintenance) have been notified, an investigation is ongoing.

On Nov 19th 2019 the aircraft had positioned to Kelowna,BC (Canada), remained on the ground in Kelowna until Jan 6th 2020, then positioned to Keflavik via Seattle,WA (USA). On Jan 9th 2020 the aircraft resumed service and had flown about 70 sectors since.

On Feb 11th 2020 The Aviation Herald received permission to publish the narrative of a passenger describing the experience on board of this flight. While granting the permission the passenger re-iterated that the landing was really smooth and that the passenger noticed the missing pin from the landing gear, too. The narrative in its entirety:

For those curious about my trip, the most exciting part was on my way home landing in Reykjavik, Iceland on flight FI529. The flight tracker on the in-flight information system said the winds were 30-50 MPH at the airport. This is fairly typical for Reykjavik. The approach was smooth and not turbulent. Normal landing speed for a Boeing 757 is 155 MPH. According to another passenger we touched down at 120 MPH which means we had a strong headwind. Everything was smooth including the landing. We touched down and then rebounded on the shocks in the landing gear. It did not feel like we left the ground again. There were the normal sounds of landing. We settled back down and the nose wheel touched, there was a loud bang and thump from the right side of the plane. It felt like we were flying again as the right wing dipped and then came back to level. The bottom of the dip was soft like a normal correction to turbulence.

As the plane slowed the right wing dropped again and stayed down. I was on the left side one row behind the wing's emergency exits. Window seat. I looked across the aisle and out the window on the right. There were sparks coming back from below the right engine. We came to a straight and smooth stop.

All the passengers were calm and quiet the entire time. The flight attendant came on the PA and told everyone to stay in their seats and listen for instructions. Anticipating having to use the emergency slides I took everything important out of my computer bag including passport, car keys, wallet, cell phone charger, Twix bar, etc. and put them in my coat pockets. I put my coat on.

The pilot came on and in a slightly shaky voice told us that as we may have guessed there was a problem with the landing gear and that we were safe to stay right where we were. Emergency personnel were on their way and we would be told what to do. He kept the left engine running a little while. They he started the auxiliary power unit and shut off the main engines. We had lights and heat the whole time. Emergency vehicles began to show up. Quiet talking and a little laughter was heard in the cabin. The pilot announced that they were going to evacuated us by mobile stairs and buses. I was disappointed I couldn't go down the slide.

We had been sitting for almost an hour, although I was not watching the clock, before the first passengers came off. They said they were stabilizing the plane. I could feel the wind shaking the plane. I saw a tug come out but I don't know where they put it. They started the evacuation by quickly unloading the rearmost few rows. They did this because the plane was unbalanced. The plane was resting on the right engine which is ahead of the point where the gear is. It was also tipped back a little. This moved the balance point forward and made the nose wheel light. I think they were afraid a strong gust could move the nose wheel sideways and cause problems getting onto the stairs.

As passengers came forward they had their luggage. They continued unloading from back to front. I put down the phone and prepared to leave. We went down the stairs and onto waiting buses. Once on the bus I took some more pics while waiting. It was only when on the bus and seeing the plane resting on the engine that I had a slight adrenaline rush.

When we got to the terminal there were a lot of staff waiting to help if needed. We were given bottles of water. They had emptied the entire wing of the terminal. As we got to the main terminal there was a person asking where I wanted to go. I said "Toronto." The couple behind me said "hotel." According to reports about a third of the passengers continued on to other destinations.

I grabbed some food and waited a long time in line but eventually made it to Toronto. Another person I knew was in line across from me. I said 'that could have gone better." She replied "it could have gone worse." Good point. A few of us were standing around discussing the event and more than a few people were eagerly listening. No announcement was made in the terminal except that all flights were delayed. No one knew there had been an accident. Not the kind of thing to tell people about to get on planes. While waiting in line to board my second flight two women behind me were complaining about the long wait. I told them that the airport could not use one of its two runways due to landing gear collapsing on a plane which had the runway blocked. I said I knew this because I had been on it. Their eyes went wide in a cartoon-like manner. No more complaining.

I went to go to my seat on the plane to Toronto but a flight attendant intercepted me and asked if I would like to move to a better seat up front. Was I on..."The flight from Berlin?" I interjected "Yes." I didn't make it to business class but I had a much nicer seat with my half of the row to myself. There was another girl from the same flight who was all the way on the right. The flight attendants checked on us more than usual.

Made it safely to Toronto while binge-watching "The Expanse." Good thing I had not downloaded the "Airport" movies from the 70's.

My opinion is that the landing was as smooth as any and that there was little cross wind. The landing in Toronto on an identical Boeing 757-200 was the same except for the gear collapse. I believed there was a mechanical failure due to maintenance but not due to the landing itself. The gear did not collapse until the plane settled down.

I found the below report (Editorial note: the passenger references this our AVH coverage about this event) which matches my recollection of the event. They had replaced the main gear on this very plane less than a month ago. Someone screwed up and didn't tighten a bolt. This pic (referencing our AVH picture showing the missing bolt) shows the brace which should have been attached to the gear.

In the end, no-one was hurt. The pilot did an excellent job of keeping the plane level and straight. It could have been much worse. I think the headwind kept the landing speed low which helped. When I look at the pic of the nose wheel I realize the pilot probably did not have great steering control due to the weight shift. I am even more impressed that he kept it straight down the middle of the runway.

Someone in the line listening to us relate the experience jokingly said he didn't want to fly with any of us. I disagreed and said that we had all used up a lifetime of bad luck and that there was no way it could happen to someone twice. I had no reservations about getting on the second plane.

Sometimes, people who travel frequently like to exchange travel stories and try to top each other with misadventures. I plan to keep this story in my back pocket for just such an occasion. If only I could have gone down the slide...

On Mar 27th 2020 Germay's BFU reported in their February Bulletin that they have joined the investigation representing the state of design of the engines.

On Apr 6th 2020 Iceland's RSNA released their interim report reporting the sequence of events:

The airplane encountered considerable turbulence at 1000 feet above MSL. The autopilot was disengaged between 600 and 700 feet above MSL and the airplane was then manually flown down towards the runway.

The airplane was flown with the nose into the wind on final approach due to crosswind conditions. Few seconds before touchdown the airplane was de-crabbed to line up with the runway heading.

The flare was normal and the airplane initially touched down on its right main landing gear. Then the left main landing gear touched the runway. Almost immediately thereafter, as the nose was gradually coming down, abnormal sound [like metal fracturing] was observed and the right side of the airplane sunk down.

The airplane speedbrake deployed momenteraly and the right engine hit the runway. The airplane then leveled off again and the nose landing gear touched the runway.

The airplane wobbled as it continued down the runway, on the left main landing gear and the nose landing gear only, as the PF fought to keep the airplane level and centered on the runway, utilizing the aileron and rudder controls.

As the airplane speed decreased, the aerodynamics of the wings and the effectiveness of the rudder and aileron control diminished, until the PF could no longer keep the airplane wings level.

The right wing sunk down again and the right engine hit the runway again. The airplane skid on the runway until it came to stop, still on the runway but with a magnetic heading of 115°.

During the ITSB (Icelandic Transportation Safety Board, aka RNSA) on-site investigation it became clear that the NUT used to fasten the SWIVEL in the lug position on the MAIN LANDING GEAR SHOCK STRUT was missing along with its mating WASHER-SPLINED.

These parts were found close to the touchdown zone.

The RNSA reported that the damage observed on the swivel and the nut "suggests that the NUT came off the SVIWEL without the NUT turning. This also suggest that the thread sizes of the SWIVEL and the NUT did not match."

Based on the FDR recordings the RNSA stated the maximum vertical load at landing was +1.28G followed by a vertical load of +0.6G while the right main gear collapsed. Following the collapse of the right main gear a maximum vertical load of +1.4G occurred.

The RNSA reported tests and research revealed:

The SWIVEL threads were undersized 1/16 inch during an overhaul in December 2008. The SWIVEL threads were then undersized again during an overhaul in November 2019, bringing it to 1/8 inch undersize.

This brought the Major Diameter of the SWIVEL threads down to 1.6241 inch per the overhaul documents. Per Boeing CMM 32-11-72, Repair 4-3, such an undersize was allowed but required a special 1/8 undersized NUT to be fabricated and used.

Initial measurements by the ITSB after the accident has shown the Major Diameter of the SWIVEL threads to be 1.622 inch.

For 1/8 inch undersize, the Minor Diameter of the NUT was required to be in the range of 1.5439 to 1.5539 inch.

Initial measurements by the ITSB after the accident has shown the Minor Diameter of the NUT threads to be 1.617 inch.

The preliminary investigation therefore indicates the NUT to be too large for the 1/8 inch undersized SWIVEL threads.

The RNSA released an immediate safety recommedation to have all landing gear overhauled by Landing Gear Technologies inspected for undersized components and mating components to match.

Related NOTAMs:
A0061/20 NOTAMR A0060/20
Q) BIRD/QMXLC/IV/M/A/000/999/
A) BIKF B) 2002071826 C) 2002081600
E) RWY 10-28 CLOSED DUE TO OBSTACLE ON RWY
REF: BIKF AD 2.12 BIKF AD 2.24.1.2-1

A0060/20 NOTAMN
Q) BIRD/QMXLC/IV/M/A/000/999/
A) BIKF B) 2002071635 C) 2002072200
E) RWY 10-28 CLOSED DUE TO OBSTACLE ON RWY
REF: BIKF AD 2.12 BIKF AD 2.24.1.2-1

Metars:
BIKF 071800Z 16025KT 4000 RA BR SCT006 BKN010 BKN031 05/04 Q0965=
BIKF 071730Z 15031G46KT 4000 RA BR SCT006 BKN010 BKN031 05/04 Q0965=
BIKF 071700Z 13042G58KT 6000 -RA BR SCT009 BKN013 BKN039 06/06 Q0965=
BIKF 071630Z 13039G54KT 4000 -RA BR SCT009 OVC013 07/06 Q0965=
BIKF 071600Z 13042G55KT 8000 BR OVC013 07/06 Q0966=
BIKF 071530Z 13042G56KT 6000 BR OVC013 07/06 Q0967=
BIKF 071500Z 13040G53KT 5000 -DZRA BR OVC010 07/06 Q0968=
BIKF 071430Z 13040G54KT 3000 -DZRA BR BKN008 OVC012 07/06 Q0970=
BIKF 071400Z 13040G54KT 3000 -DZRA BR BKN008 OVC012 07/06 Q0970=
BIKF 071330Z 13031G43KT 4000 -DZRA BR BKN013 OVC040 07/05 Q0972=
BIKF 071300Z 13029G45KT 4000 -DZRA BR BKN014 OVC040 07/05 Q0973=

Right Main Landing Gear - Side Strut Swivel disconnected from the Shock Strut (Photo: RNSA):


Side Strut Swivel – Missing the Nut and the splined Washer (Photo: RNSA):


The right main landing gear in detail, a bolt is missing:


The aircraft sitting on the runway:






Passenger photo after stand still:
Incident Facts

Date of incident
Feb 7, 2020

Classification
Accident

Airline
Icelandair

Flight number
FI-529

Aircraft Registration
TF-FIA

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

This article is published under license from Avherald.com. © of text by Avherald.com.
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