Delta B752 at Ponta Delgada on Aug 18th 2019, hard touch down causes creases in fuselage

Last Update: May 4, 2020 / 14:27:46 GMT/Zulu time

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Incident Facts

Date of incident
Aug 18, 2019

Classification
Accident

Flight number
DL-414

Aircraft Registration
N543US

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

A Delta Airlines Boeing 757-200, registration N543US performing flight DL-414 from New York JFK,NY (USA) to Ponta Delgada (Portugal), landed on Ponta Delgada's runway 12 at 08:24L (08:24Z) but suffered a hard touch down. The aircraft rolled out and taxied to the apron. There were no injuries, the aircraft sustained substantial damage however.

A replacement Boeing 757-200 registration N538US positioned from Atlanta,GA (USA) to Ponta Delgada to perform the return flight.

On Aug 19th 2019 the FAA reported the occurrence was rated an accident, the aircraft sustained substantial damage when it landed hard in Ponta Delgada.

Portugal's GPIAA released their summary final report (Portugese and English) concluding the probable causes of the accident were:

From the aircraft assessment condition, the data collected from the crew and from the airfield available data, the investigation establishes as most probable cause for the event, the excessive nose landing gear derotation rate, resulting in a hard landing with nose gear overload.

Contributing factors were:

- the clearance for RNAV (GNSS) approach on runway 12 when the crew have prepared the ILS approach on runway 30;

- PF piloting technique with excessive corrections of attitude and thrust corrections, namely the excessive nose down elevator input after MLG touchdown;

- For the repeatedly PF corrections, may had contributed the lateral northeast crosswind effect during the landing (050º with 16kt variable between 020º and 080º);

- the aircraft's mass on landing contributed to the consequences on the inflicted damage to the primary structure.

The engines thrust reduction during the derotation movement, enhancing the excessive moment around the aircraft lateral axis cannot be excluded as a possible contribution factor.

The GPIAA reported:

The crew anticipated and prepared an ILS approach to runway 30, however, on the descent to Ponta Delgada, the flight was cleared for RNAV (GNSS1) Z approach for runway 12.

Due to the aircraft estimated landing weight of 196000lb and the maximum authorized landing weight (MLW) of 198000lb, the crew reviewed the landing parameters calculating the reference speed (Vref) with 133kt, the landing distances and opting for the brake 4 on the aircraft automatic brake system, based on the company guidance for the destination airport.

The reported wind to the crew was 050º with 16kt, variable between 020º and 080º, with a local temperature of 21ºC.

During the approach, around 1500ft, the co-pilot who assumed the position of the pilot flying (PF), uncoupled the autopilot and followed the operator standard operational procedures SOPs.

On short final, some speed variations were felt with the respective corrections in the flight controls and engine power adjustments by the PF closely followed by the pilot in command (PIC) adding verbal inputs.

The initial touchdown was on the left main gear, followed by the right main gear, both contacts were considered normal. Right after that, the aircraft nose abruptly pitched down and the nose landing gear touched hard on the runway.

The aircraft was on the runway centreline and, after the hard touch of the nose landing gear felt and commented by the pilots, it decelerated rapidly. Right after that and still without realizing what had happened, at a speed of approximately 100kt, the pilot in command (Captain) took control of the aircraft.

The aircraft, after deceleration, reversed the direction of travel on the runway and headed for the assigned parking space, without any reports of
anomalies by the crew.

During the post-flight walk-around, damage was observed on the lower front fuselage near the nose landing gear and on the upper central fuselage in the area in front of the wing.

The GPIAA analysed the FDR data, that the main gear touched down at +1.53G within normal values, the vertical acceleration increased to +1.88G with the nose gear touch down. The GPIAA wrote:

several movements in the control column, with increasing amplitude, being that the variation of values of -5.0 (nose down) occurs immediately before the vertical acceleration develops a sudden change (contact with the ground) and a correction is made for +7.40 (nose up) right afterwards;

it was possible to verify that, for the same period of time, the pitch angle changed significantly from +3.9 to -1.4.

The FDR data collection rate of only one sample per second did not allow to conclude unequivocally whether the application of pressure on the auto brakes was a direct factor in order to determine whether the consequent moment created with the nose down during braking influenced the static load passed to the primary fuselage front structure.

The GPIAA argued: "After evidence collection and the performed tests, the investigation team considers that the event has a low level of complexity and that the extractable safety learning is limited, being sufficiently covered by the remit of the work carried out so far, thus allowing to present its results in a shorter period and in a simpler way than the formal ICAO Annex 13 format."

Metars:
LPPD 181000Z 05011KT 020V080 9999 FEW014 BKN035 22/17 Q1021=
LPPD 180930Z 04015KT 9999 FEW014 SCT035 21/17 Q1021=
LPPD 180900Z 04012KT 010V070 9999 FEW014 SCT035 21/17 Q1021=
LPPD 180830Z 04012KT 020V080 9999 FEW010 SCT040 21/17 Q1020=
LPPD 180800Z 04013KT 9999 FEW010 SCT040 21/17 Q1020=
LPPD 180730Z 05012KT 9999 FEW006 SCT010 21/18 Q1020=
LPPD 180700Z 04014KT 9999 FEW006 SCT010 20/18 Q1020=
LPPD 180630Z 05011KT 010V070 9999 FEW006 SCT010 20/18 Q1020=
LPPD 180600Z 04012KT 010V070 9999 FEW006 SCT010 20/19 Q1019=
LPPD 180530Z 05013KT 9999 -DZ FEW006 SCT010 BKN040 20/19 Q1019=
LPPD 180500Z 04012KT 360V060 9999 -DZ FEW006 SCT010 BKN040 20/19 Q1020=
LPPD 180430Z 04010KT 360V060 9999 -DZ FEW006 SCT010 BKN040 20/19 Q1019=
LPPD 180400Z 05009KT 020V080 9999 -DZ FEW006 SCT010 BKN040 21/19 Q1019=
LPPD 180330Z 04010KT 010V070 9999 -SHRA FEW006 SCT010 BKN040 21/19 Q1019=
Incident Facts

Date of incident
Aug 18, 2019

Classification
Accident

Flight number
DL-414

Aircraft Registration
N543US

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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