There is an increasing sensitivity to the challenges posed by the language of examination papers and of instruction in scientific subjects, especially for non-native speakers of English. It has been observed that in addition to technical subject-specific vocabulary, non-technical words such as instructional verbs have been sources of difficulty, and there are indications that other "ordinary" English words cause problems. For many years the aerospace industry has striven to make its manuals understandable and unambiguous to non-native speakers, a goal shared by writers of examination papers. To achieve this, the industry uses Simplified English, a controlled language with limited vocabulary and restricted grammatical rules. While recognising the limitations of this approach, the authors considered that by testing examination papers against the rules of Simplified English, it might be possible to identify areas of potential difficulty for non-native speakers. This paper describes the results of a study which tests past examination questions using software based on AECMA Simplified English, the controlled language in established use in the British aerospace industry. The results identified many lexical items which were not in the original list of "Approved words". Some of these were technical words and others were non-technical terms which are in common use in an engineering context. However, some were potential problem sources, including implicit instructions and vague or ambiguous words. Software alerts that related to sentence structure, in particular those related to sentence complexity, indicated that some sentences had additional problems. (Contains 1 note.)