Norwegian B738 near Belfast on Jun 16th 2018, hydraulic failure

Last Update: June 15, 2020 / 16:09:30 GMT/Zulu time

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Photo of Norwegian Air International EI-FHD, Boeing 737-800 — Norwegian Air International EI-FHD, Boeing 737-800 (Photo credit: Chris.Strickland / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jun 16, 2018

Classification
Incident

Cause
Hydraulic failure

Airline
Norwegian Air International

Flight number
D8-6241

Departure
Keflavik, Iceland

Destination
Madrid, Spain

Aircraft Registration
EI-FHD

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

A Norwegian Air International Boeing 737-800, registration EI-FHD performing flight D8-6241 from Keflavik (Iceland) to Madrid,SP (Spain) with 152 people on board, was enroute at FL350 about 20nm north of Belfast International (Northern Ireland) when the crew reported a hydraulic failure and decided to divert to Birmingham,EN (UK). The aircraft landed safely in Birmingham about one hour later. The aircraft stopped on the runway, emergency services foamed the aircraft when a hydraulic leak was seen from the left main gear.

The airport reported the aircraft diverted due to hydraulic failure. Flights were suspended for about 4 hours as result.

The airline reported a techncial issue.

On Jun 15th 2020 the Icelandic RNSA released their final report concluding the probable cause of the serious incident was:

The ITSB believes that the cause of the serious incident to be that the aircraft incurred Foreign Object Damage (FOD).

The ITSB also believes the FOD occurred as it ran over debris during its take off roll, most likely when it passed between taxiway S-2 and high speed taxiway A-1 on RWY 01 at Keflavik Airport.

The RNSA reported:

During the takeoff roll, at Vr3, an unusual vibration was felt by the flight crew from the nose landing gear. Vibration was also noticed by two cabin crew members, sitting forward of the over wing area. A third cabin crew member, sitting in the aft galley, also reported feeling the aircraft rattle during the takeoff run.

After the aircraft had lifted off and the landing gear was being retracted, the pilots noticed that the antiskid INOP light illuminated.

The PM performed QRH4 14.1 Antiskid Inoperative non-normal check list and the After Take Off Checklist. The climb was continued, with the deviation of a left turn from departure routing to avoid CBs5.

When the aircraft reached FL100 the PM performed the 10,000 feet checks6, during which he identified a low quantity (20% remaining) in hydraulic system A of the aircraft (HYD A).

The hydraulic pressure of system A was still normal, or 3000 psi. The flight crew suspected a hydraulic leak in the engine-driven pump or its related lines. HYD A ENG 1 LOW PRESSURE light illuminated right after. The flight crew referred to the QRH, HYDRAULIC PUMP LOW PRESSURE non-normal checklist 13.1.

While the flight crew was executing the checklist, ATC7 informed them that tire rubber had been found on RWY 01 at BIKF after they took off. Initially the flight crew only suspected a tire burst. The flight crew informed ATC of their hydraulic problems. Subsequently in another communication, ATC also relayed information that a metal piece had also been found on the RWY.

The flight crew performed evaluation of the situation, ANTISKID INOP + Tire burst + Loss of HYD A QTY (20% remaining and possible future loss of HYD system A) + metal piece on the RWY. They concluded that the aircraft was possibly damaged in the wheelwell compartment area or the flaps. The flight crew then reviewed other aircraft systems and found no other faults.

The flight crew then reviewed the option of returning to BIKF. When the aircraft took off from BIKF, it had been raining. In addition there was low visibility and CB’s in the area, and the airport runways were wet, possibly slippery and loose earth on the side of the runway due to continuous rain (in case of runway excursion).

The flight crew performed various Non Normal performance landing calculation using the EFB, including (Antiskid inop FL40, Loss of HYD system A FL40). Due to tire burst they added margins to these figures.

The flight crew discussed the braking action of the A/C after landing, taking into consideration: difficult aircraft controllability after touch down with tire burst, braking action with no antiskid, ground spoilers inop, thrust reverser deployment at slower rate and thrust asymmetry during thrust reverser deployment. Possible runway excursion. Possible fire of LDG gear after landing.

This led the flight crew to prefer a long, dry runway with good visibility.

The flight crew therefore concluded, as all other systems were operating normally, that BIKF would not be the best choice for landing with compromised systems. The flight crew therefore decided to continue the flight to Europe, but started looking for diversion options in the United Kingdom or Ireland.

The crew subsequently decided to divert to Birmingham,EN (UK). While enroute to Birmingham the hydraulic quantity and pressure in system A were completely lost. On approach to Birmingham the crew performed a manual gear extension. The RNSA described the sequence of events:

After the landing gear extension the flight crew received three green lights on the aft overhead panel for the LH MLG9, RH MLG10 and the NLG11. However on the center panel, only two green lights illuminated, for the RH MLG and the NLG. From this, the flight crew deduced that they had all three landing gears down and locked and that they had damage on the LH MLG.

The flight crew then reviewed the landing technique to be used. The Commander intended to land on the RH MLG first due the compromised LH MLG. They also discussed landing distance, manual speed brake deployment, symmetrical braking action, reverse thrust usage, possible scenarios like fire or runway excursion and possible evacuation of the aircraft. The flight crew started the APU.

When the aircraft was fully configured for the landing with the flaps at 40, the Commander flew the aircraft down a long final approach. The flight crew asked ATC to verify if the three landing gears were in the down position using binoculars. ATC confirmed that all three landing gears were down. About thirty seconds before the landing the PM notified the cabin to brace for impact.

When the aircraft landed, it first landed on the RH MLG as the Commander had intended before it also came down on the LH MLG followed by the NLG. During the landing, the left wing ground spoilers did not deploy. In addition tire debris was released from the LH MLG after it touched down on the runway.

The aircraft came to stop on the runway. The flight crew set the APU on buses and shut down the engines. The fire brigade sprayed fire extinguishing agent onto the main landing gear.

The RNSA reported: "Subsequent to the serious incident both RWY 01 at Keflavik Airport and RWY 15 at Birmingham Airport were inspected and all debris found on or around the runways removed. The ITSB received the located debris from Keflavik Airport along with information about where it was located. "

The RNSA reported based on flight data recorder that 16 seconds after becoming airborne a leak of hydraulic system A became apparent.

Several pieces of debris were recovered from the runway in Keflavik, however, 3 pieces could not be linked to the aircraft. The RNSA wrote:

The ITSB could not explain the following debris found and therefore considers them as foreign objects to aircraft EI-FHD:

- 16 cm long plastic part (in two pieces): The ITSB could not identify this plastic part

- 9.5 cm long metalic PIP pin: The ITSB could not identify this PIP pin as part of the aircraft

- Bi-hex bolt: The ITSB could not identify this bi-hex bolt as being missing from the aircraft