The Nimrod Review - Official Documents

The Nimrod Review
Life Extension Programme
23.11
23.12
23.13
23.14
552
XV230 was the first Nimrod to enter service in 1969 (in MR1 form). XV230 underwent the MR2 conversion
programme in 1981. At the time of the accident in September 2006, XV230 was, therefore, 37 years old.
The Nimrod MR2 has a ‘Safe Life’ based upon its structural integrity, managed through the consumption of
platform’s Fatigue Index (FI) but has no specific flying hour life. 7
A Nimrod platform Life Extension Study was undertaken by BAE Systems in 1990. A life extension exercise
seeks to increase the limiting elements of the platform’s life (fatigue, landings, cycles etc). The BAE Systems Life
Extension Study in 1990 concluded that there was little doubt that the Nimrod MR2 airframe and systems were
essentially capable of extended life, well into the 21st Century, but that a programme of work would have to be
undertaken to ensure that the fleet life was not curtailed by fatigue, corrosion, or excessive support costs. 8 This
may, or may not, have had an effect on the platform’s Out-of-Service Date (OSD).
Nim(ES)AWS(AV)Con2 confirmed to the Review that, since BAE Systems’ 1990 report, there has been no other
life extension study undertaken on the Nimrod. There was, however, an OSD extension study. An OSD extension
study investigates whether or not the platform’s current usage rates (fatigue, landings, cycles etc) will allow the
OSD of the platform to be extended. Regrettably, of the two files relating to the Nimrod OSD extension study,
one was destroyed on 24 May 20059 and the other was located and reviewed, but did not contain any OSD
extension data. 10
Ageing Aircraft Audits
Regulations
23.15
Joint Service Publication (JSP) 553 mandates that IPTLs conduct Ageing Aircraft Structural Audits (AAAs).
Periodicity is defined as initially after 15 years from the in-service date, and every 10 years thereafter until the
aircraft is out of service, with the requirement that the audit activity is to be completed within a 3-year period.
However, whilst JSP553 sets out the requirement to undertake an AAA, it refers only to aircraft structures.
Although the AAA requirement was extended to include aircraft systems around September 2006, with the
specific requirements set out in the JAP 100A-01, JSP553 has yet to be updated to include the additional
requirements, even though it is the higher level policy document.
23.16 AAAs, as defined in JAP 100A-01, comprise Structural Audits, Aircraft Systems Audits ( e.g. mechanical, avionics
and weapons), and Propulsion System Audits. For some aircraft, this undertaking will be closely related to the
management of obsolescence and life extension programmes. The JAP 100A-01 defines an AAA as:
23.16.1 A periodic, independent assessment of the airworthiness of the aircraft and its systems as they age.
23.16.2 A vital through-life management (TLM) activity that is to be reflected in the aircraft’s TLM Plan.
23.16.3 An activity intended to bring together the routine management activities, often carried out in isolation,
in order to build a coherent picture of the state of the aircraft fleet.
23.16.4 An activity that should also seek to identify patterns or trends that point to future integrity problems.
23.16.5 An activity to identify significant risks to the aircraft and its systems: it is not simply to record the status
of the aircraft and its systems, management processes, technical information and documentation.
These risks are to include both current and potential risks to the planned OSD being reached.
23.17 JAP 100A-01, Chapter 16.4, paragraph 1.1, provides: “The risk to airworthiness, cost and operational availability
due to ageing of aircraft in service is partly mitigated by maintenance activities, however, the insidious nature
of degradation and the interaction of apparently unrelated ageing processes is often only found by rigorous
periodic audit of trend data, procedures and, if necessary the aircraft’s physical condition”.
7 BOI Report, Exhibit 25; and the IPT’s response of 15 March 2007.
8 BAES report 807/RGJ/1609/11 “Extension of Nimrod MR Mk 2 Operational Life until circa 2025”, dated 19 September 1990.
9 DLO(Strike)(Wyt)/512740/13 Part A.
10 DLO(Strike)(Wyt)/512725/17 Part A.