ASN Wikibase Occurrence # 202557
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| Date: | Friday 5 June 2015 |
| Time: | 18:57 |
| Type: |  Boeing 737-522 |
| Owner/operator: | Aero Contractors |
| Registration: | 5N-BLE |
| MSN: | 26672/2343 |
| Year of manufacture: | 1992 |
| Fatalities: | Fatalities: 0 / Occupants: 113 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | en route Kaduna Airport -
 Nigeria
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Lagos-Murtala Muhammed International Airport (LOS/DNMM) |
| Kaduna Airport (KAD/DNKA) | |
| Investigating agency: | AIB Nigeria |
| Confidence Rating: |  Accident investigation report completed and information captured |
Aero Contractors flight NIG181, a Boeing 737-500 aircraft, took off from Lagos, Nigeria, at 18:28 hrs local time with 108 passengers and 5 crew on board. The First Officer was the pilot flying.
During the initial climb, the Captain observed that the cabin rate of climb was zero but later indicated normal. However, the First Officer reported that on reaching FL150, he observed that the cabin altitude was indicating about 3000ft and since this occurred at low altitude, they decided to monitor during climb.
Approximately 23 minutes after becoming airborne and climbing through FL330, the cabin altitude warning horn came on and the Captain took control of the aircraft. The flight crew donned their oxygen masks, set the regulators to ON/100% and crew communication was established as required by the procedures of the approved Quick Reference Handbook (QRH) and Airplane Flight Manual (AFM).
According to the account of the purser, she went into the lavatory and observed that the sink was full, which she tried to drain. She got out of the lavatory and observed that her oxygen mask had dropped. She then checked the cabin area and observed that the business class passengers’ oxygen masks had also dropped. She immediately took her seat, donned her mask and briefed the passengers. Thereafter, she called the cockpit but there was no response.
Emergency descent to an altitude of 10,000ft was initiated. The Captain briefed the purser and made an announcement to inform the passengers that the flight was being diverted to Abuja.
The aircraft landed safely in Abuja at 19:32 hrs, taxied to the ramp and parked. Crew and passengers disembarked without injury.
On 5th June, 2015; the day of the incident, engine no.2 was changed at Lagos due low time remaining and replaced with another engine. The engine post-installation procedure required that the Pressure Relief Shut-Off Valve (PRSOV) should have been checked after the engine change to confirm that it is in the OPEN position. The engine installation procedure as contained in the AMM Section 71‐00‐02 requires a series of post-installation tests to verify correct operation. One of these tests is the Pneumatic Leak Test. This test requires that the PRSOV be manually wrenched to the OPEN position. The PRSOV will remain open when there is pneumatic pressure upstream of the PRSOV.
There is no evidence to show that these procedures were followed by the maintenance engineers during the engine installation. Also, there was no evidence that a duplicate inspection was carried out to confirm that appropriate procedure had been followed during the engine installation.
Causal Factor:
The inadvertent failure to discover that the PRSOV was in the LOCKED CLOSED position after the engine change.
Contributory Factor:
Failure to recognise that the number 2 bleed pressure was zero after engine start and subsequent failure to monitor the pressurisation system during climb.
Accident investigation:
 |
|
Sources:
History of this aircraft
Other occurrences involving this aircraft
| 21 August 2010 | 5N-BLE | Aero Contractors Company of Nigeria | 0 | Jos Airport (JOS/DNJO) | |
min |
| Runway excursion | ||||||
| 21 March 2021 | 5N-BLE | Aero Contractors | 0 | near Kano-Aminu Kano International Airport (KAN/DNKN) | |
unk |
| Bird strike | ||||||
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 05-Dec-2017 18:43 | harro | Added |
| 05-Dec-2017 18:47 | harro | Updated [Narrative] |
| 05-Dec-2017 19:53 | harro | Updated [Narrative] |
Corrections or additions? ... Edit this accident description
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