TUI B738 near Paris on Oct 10th 2018, IRS and associated systems failure

Last Update: October 31, 2019 / 18:25:13 GMT/Zulu time

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Photo of TUI Airways G-FDZF, Boeing 737-800 — TUI Airways G-FDZF, Boeing 737-800 (Photo credit: Aircaft @ Gloucestershire Airport By James / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Oct 10, 2018

Classification
Report

Airline
TUI Airways

Flight number
BY-2350

Departure
Manchester, United Kingdom

Destination
Palma Mallorca, Spain

Aircraft Registration
G-FDZF

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

A TUI Airways Boeing 737-800, registration G-FDZF performing flight BY-2350 from Manchester,EN (UK) to Palma Mallorca,SP (Spain), was enroute at FL390 about 80nm west of Paris (France) when the crew decided to return to Manchester due to a right hand IRS and associated system failures. The aircraft landed safely in Manchester about 50 minutes later.

The UK AAIB released their final bulletin combing this occurrence into another occurrence the previous day, see Report: Ryanair B738 over Bay of Biscay on Oct 9th 2018, altitude deviation, IRS fault and associated system faults and concluded:

On EI-GJT, the IRS of the left ADIRU suffered a fault which led to an erroneous calculation of position. On G-FDZF, the ADIRU was contaminated by fluid ingress. In both cases, this resulted in the display of faulty attitude information on the commander’s PFD, and the supply of erroneous information to several aircraft systems. The problems were contained through manual flight and the use of standby instrumentation. Although action could have been taken to restore reliable attitude information to the commander’s PFD, such action was not directed from within the QRH. The training given to the crews discouraged them from acting unless directed by the QRH, so this lack of relevant information in the QRH contributed to the situation.

The AAIB reported the aircraft was operating a ferry flight from Manchester to Palma Mallorca. The co-pilot was the pilot flying (PF).

Shortly after reaching the cruise flight level, AP B disconnected, attitude comparator annunciations appeared on the PFDs, both Electronic Engine Controls (EEC) changed to alternate mode, tcas fail appeared on the Navigation Display (ND) and a HDG fail flag appeared on the standby compass. Neither AP could be re-engaged, so the crew continued in manual flight. On checking the Master Caution recall a mach trim caption was present indicating a single lane failure in the Mach Trim system.

The crew completed the QRH actions for the eec altn caution. Their interpretation was that there was a technical issue with the right IRS, but they did not conduct any IRS or Flight Instrument non-normal checklist (NNC) as the QRH contained no relevant information.

They decided to return to Manchester, and during preparations for the approach it became apparent that the autobrake would not arm, further evidence of an IRS issue.

For a complete summary of the report see Report: Ryanair B738 over Bay of Biscay on Oct 9th 2018, altitude deviation, IRS fault and associated system faults, please.