Stratton, Guy2019-03-212019-03-212019-03-14Gratton GB. (2019) A pitch trimmer can cause a catastrophic structural failure in an aeroplane, but this is avoidable. The Aeronautical Journal, Volume 123, Issue 1260, February 2019, pp. 174-1900001-9240https://doi.org/10.1017/aer.2018.157https://dspace.lib.cranfield.ac.uk/handle/1826/14002This paper investigates the potential of a lever-type pitch trimmer to cause an overstress in light and microlight aeroplanes. It concludes that this potential exists and could potentially cause a catastrophic structural failure – with the evidence from one reported fatal accident suggesting that this may have already happened. However, it is shown that this need not be the case, with restricted nose-up control authority, high manoeuvre stability and the use of a trim wheel (as opposed to a lever) with a restrictive rate of control input shown as three methods, most likely in combination, by which this potential can be removed. Suggestions are made for airworthiness standard wording which might be used to ensure adequate safety of future aircraft designs.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Flight testPitch trimmerLongitudinal stabilityStructural failureCertificationMicrolight; VLAPart 23Article