Aviation safety issues and actions

Fuel quantity assessment methods

Issue number: AO-2018-019-SI-01
Issue owner: Skippers Aviation
Transport function: Aviation: Air transport
Background: Investigation Report AO-2018-019
Issue release date: 27 May 2021
Current issue status: Closed – Adequately addressed
Issue status justification:

The ATSB is satisfied that Skippers’ amendments to, and increased focus on, fuel management policy and procedures addresses the safety issue risk with regard to the limitations of its fuel quantity assessment methods.

Safety issue description

Although the operator had specified multiple methods of cross-checking fuel quantity gauge indications for its C441 fleet, there were limitations in the design, definition and/or application of these methods. These included:

  • The primary method used (indicated versus calculated fuel) was self-referencing in nature, and not able to detect gradual changes in the reliability of fuel quantity gauge indications.
  • Pilots did not record (and were not required to record) sufficient information on flight logs to enable trends or patterns in fuel quantity gauge indications to be effectively identified.
  • Pilots did not routinely cross-check information from fuel quantity gauge indications with information from the independent fuel totaliser.

Proactive action

Action number: AO-2018-019-NSA-067
Action organisation: Skippers Aviation
Date: 27 May 2021
Action status: Closed

During the investigation, Skippers Aviation advised that:

  • A company memorandum was issued directing all Conquest pilots to ensure that the minimum fuel to be uplifted was the total minimum as calculated by flight plan. The only exception was if this quantity would exceed full tanks or if a fuel quantity gauge calibration was conducted. This was an interim measure until the circumstances of the occurrence were ascertained. This was removed following confirmation of fuel exhaustion and no other mechanical cause.
  • The fuel quantity comparison check frequency was increased to every 30 +/- 7 days. The check required fuel tanks to be filled to capacity to enable a comparison check of gauge indications against a known quantity. The gauges were required to indicate with 5% of the known capacity of the tanks to pass the check.
  • Weekly reporting requirements (from Broome base to Perth headquarters) were implemented. This included various operational matters to provide increased oversight of Broome operations.
  • The Broome Senior base pilot increased surveillance of Broome line pilots.
  • Flight operations increased audits of Broome operations to monitor standards and compliance.
  • Fuel usage record keeping requirements were amended. Indicated and calculated fuel quantities were to be recorded after each landing and each refuel.
  • A tolerance of 100 lb was introduced for pilots to reference when comparing corrected indicated quantity to quantity derived from the totaliser figures.
  • Following consultation with relevant authorities, additional fuel drains were installed in the hopper tanks to enable fuel quality testing if fuel within the hoppers.

In April 2021, during the directly involved party process, Skippers confirmed that the actions previously advised had taken place (or were continuing). In addition, Skippers advised that, during line-oriented flight training there is an increased focus on:

  • The Gross Error Check (580 lbs transfer pump fail annunciator) after shutdown and prior to start up with fuel boost pumps off.
  • Input of Fuel on Board figure in Garmin 530 and cross checking against fuel gauges after each sector to compare burn figure.
  • Fuel System knowledge in general but Fuel Level Low and Transfer Pump Fail annunciators in particular.
  • Fuel quality checking.
  • A fuel emergency scenario on every flight.
Last update 27 May 2021