Safair B734 at Johannesburg on Dec 10th 2019, "rain" in the cockpit turns into smoke

Last Update: September 10, 2020 / 19:55:50 GMT/Zulu time

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Incident Facts

Date of incident
Dec 10, 2019

Classification
Incident

Airline
Safair

Flight number
FA-369

Aircraft Registration
ZS-DMI

Aircraft Type
Boeing 737-400

ICAO Type Designator
B734

A Safair Boeing 737-400, registration ZS-DMI performing flight FA-369 from Johannesburg to Port Elizabeth (South Africa) with 166 passengers and 6 crew, was climbing through FL280 out of Johannesburg when the crew stopped the climb due to a water leak in the cockpit, the leaking water ingressing some aircraft systems resulting in smoke in the cockpit. The aircraft landed safely back on Johannesburg's runway 03L about 30 minutes after departure.

South Africa's CAA have opened an investigation into the occurrence.

On Feb 24th 2020 the SACAA released their preliminary report summarizing the sequence of events:

While climbing through 28 000 ft, still within the Johannesburg FIR water that have accumulated in the left drip tray (above the pilot-in-command head) started to leak from the drain pipe on the left side onto the avionics/instrumentation of the aircraft. The water caused some arcing, which resulted in smoke emanating from the behind the instrument panel on the left side. Following a brief discussion between the two members they declared a Mayday and requested to returned to FAOR. The crew members opted to make use of their respective oxygen masks and landed safely back at FAOR thirty two (32) minutes after take-off, at 0506Z.

The captain (46, ATPL, 15,791 hours total, 381 hours on type) was assisted by a first officer (44, ATPL, 6,025 hours total, 150 hours on type).

On Sep 10th 2020 the SACAA released their final report concluding the probable cause of the serious incident was:

The tubing was found to have been exposed to prolonged environmental conditions as well as ageing, which caused it to become hard and brittle, and subsequently became dislodged from a connection fitting which allowed water from the overhead drip pan to leak onto the back of some of the instrumentation situated on the left side (pilot-in-command) of the cockpit. This caused arcing (flash was seen) followed by smoke in the cockpit.

The SACAA summarized their conclusion also as: "The investigation revealed that during the climb phase, the water drain pipe connected to the overhead cockpit drip pan became dislodged and water dripped onto the aircraft’s instrumentation panel, causing smoke in the cockpit."

The SACAA analysed:

The crew was properly rated and qualified to conduct the flight. At approximately 04:48:22Z, which was 12 minutes after take-off, the crew declared an emergency by broadcasting a Mayday, as well as requesting permission to return to FAOR while under radar control. The aircraft was instructed to turn right, descend to FL110 with no speed restrictions applicable. The crew then followed the emergency procedures for smoke, fire and fumes in the cockpit as contained in the QRH (see Annexure A).

The PIC first reported that there was fire in the cockpit; two seconds later, he said it was smoke in the cockpit, and not fire. By changing his observation from fire to smoke within seconds indicated that there might have been a flash or a spark visible when the water, which must have been a small amount, first made contact with the instrumentation/avionics. Following a flash, which was observed by the PIC, smoke then started to emanate from behind the instrument panel. There was no fire that required any radical intervention by the crew, i.e., making use of fire extinguishing units to contain the fire.

The crew fitted their smoke goggles, which incorporated oxygen masks. This observation was made when listening to the audio communication between the flight deck crew and the radar controller. The FO also confirmed that he was on oxygen, which was audible during communication with the radar controller. The oxygen masks in the cabin were not deployed as the smoke was limited to the cockpit. The smoke dissipated relatively quickly from the cockpit and it was possible for the crew to remove their smoke goggles before landing at 0506Z on Runway 03L. The decision by the crew to opt to return to FAOR was the correct one as the serious incident occurred shortly after take-off and the aircraft had to be inspected to determine the cause of flash/spark which was followed by smoke. FAOR was also the primary maintenance base for the operator. When the flight crew have to deal with any in-flight fire, smoke or bad odour/fumes, the crew needs to make a quick decision to either divert and (i) land at the nearest suitable aerodrome, or (ii) land immediately, which implies an immediate diversion to land on a runway, (iii) or landing could be imminent, this could include an off runway landing (i.e., forced landing).

The aircraft flew for the first time on 8 May 1989 and was, therefore, in service for 30 years and 6 months when this serious incident occurred. From the aircraft history, which is tabled in sub-heading 1.6 of this report, it could be seen that the aircraft was registered with several airlines which operate from different geographical locations around the globe. Looking at the colour of the tubing that became dislodged from the fitting as illustrated in Figure 5 of the report, it differs substantially from the tubing which could be seen in Figure 6, which was taken from the cockpit of another aircraft of a similar type.

The tubing that was used in this application most probably became increasingly brittle as it was exposed to ultraviolet light for prolonged periods, as well as cold temperatures, which would have degraded the tubing by changing its properties, and which would have included its tensile strength and colour. Ageing of the tubing would also have had an effect as all polymers or plastics undergo some amount of degradation over time, which would cause the tubing to become less flexible and eventually split or crack.

At the time of this serious incident, the aircraft had been in service for 30 years and 6 months since new, of which 2 years were with the South African operator (C of R was issued on 14 November 2017). The tubing was an on-condition item and no record was available that the tubing on this aircraft was replaced since the aircraft was registered in South Africa. The possibility does exist that this tubing was never replaced since this aircraft entered service for the first time in 1989. It was evident from the appearance (discolouring) of the tubing that it had been subjected to prolonged environmental exposure/conditions, (i.e., ultraviolet light and cold weather conditions), as well as ageing.

On the day of the serious incident flight, it was raining at FAOR during start-up, taxi and take-off, as well as when the aircraft was en route to FAPE. The crew indicated in their statement that there was light rain with a cloud base of 200ft AGL at the time of take-off. These conditions were nothing out of the norm. With the aircraft being parked outside for some time prior to the flight, there might have been a possibility that a small amount of water could have accumulated on the upper cockpit drip pan.
Incident Facts

Date of incident
Dec 10, 2019

Classification
Incident

Airline
Safair

Flight number
FA-369

Aircraft Registration
ZS-DMI

Aircraft Type
Boeing 737-400

ICAO Type Designator
B734

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