Investigation and systematization of factors leading to the separation of aircraft engines fan cowls during takeoff

The main objective of the work was to identify and investigate the direct and indirect causes of engine fan cowl separation on single-aisle aircraft of foreign and domestic manufacture during the takeoff roll and takeoff.

The paper examines the loss of turbofan engine fan cowl doors on single-aisle aircraft during the takeoff roll and initial climb as a systemic operational phenomenon arising from the interaction of design solutions, maintenance conditions, and human factors. It is established that the modern power plant layout, determined by the need to reduce the risk of ground-induced vortex formation and foreign object ingestion into the engine inlet, results in reduced clearance and degraded ergonomics of fan-cowl latch operations. In combination with maintenance-related errors and a range of operational circumstances, this increases the likelihood of omitting the fan-cowl closing/locking step and the subsequent cowl separation.

The paper also considers the effect of vortex flow at aircraft engine inlets and its influence on contemporary power plant layout on aircraft. A cause-and-effect relationship was identified between the current under-wing engine arrangement and, in some cases, the fan-cowl latches remaining unlocked during the takeoff roll on the runway.

To better understand the causes, conditions, and consequences of such events, a detailed review was conducted — based on the official investigation — of an incident involving separation of the left engine fan cowl doors on aircraft RA-89112 on 12 January 2020. The factors contributing to the incomplete execution of the fan-cowl closing procedure by maintenance personnel were analyzed and structured. In addition, brief information is provided on all fan-cowl separation incidents recorded in the operational history of the RRJ-95B aircraft.

To assess the criticality of this category of events, a risk-oriented approach was applied using the ARMS Event Risk Classification (ERC) matrix. The analysis and decomposition of the specific incident, together with the calculation results, showed that the effectiveness of the remaining preventive measures acting as barriers between the event and the most likely accident-related outcome is minimal; depending on circumstances, the consequence could range from a serious incident to, in an unfavorable scenario, a catastrophe.

The results of this study may be used to develop proposals aimed at strengthening technical and organizational-procedural prevention barriers, including improving elements of the Safety Management System (SMS), developing methods to enhance human-environment interaction (the SHELL model), and updating flight and maintenance operation manuals. Taken together, these measures can play a significant role in improving flight safety and increasing the efficiency of the aviation industry

1. Accident & Incident Data: Federal Aviation Administration (2023). Available at: https://www.faa.gov/data_research/accident_incident (accessed 20 November 2025).

2. Colehour J. L., Farquhar B. W. (1971). The Inlet Vortex. Journal of Aircraft. 1971. 1.

3. Diachkov D. V., Zolotarev O. V. (2020). Analysis of statistics of air crashes based on the study of many factor. Physics and Technology Informatics (CPT2020): Proceedings of the 8th International Conference. 289-320. DOI 10.30987/conferencearticle_5fd755c09f2c91.06817396. (in Russian)

4. European Union Aviation Safety Agency (EASA) Available at: https://www.easa.europa.eu/en/home (accessed 21 November 2025).

5. Evdokimov A. I., Kretov V. V., Novitsky S. M. (1992). Analysis of the contamination of airfields based on Air Force aviation with foreign objects. The problem of protecting gas turbine engines from damage by foreign objects. Collection of reports of the All-Union Scientific and Technical Conference. Zhukovsky. 1992. (in Russian)

6. Evdokimov A. I., Novitsky S. M., Popov V. A. (1995). Characteristics of foreign objects appearing on airfield surfaces during operation: Design and control systems of the gas turbine engine. Collection of scientific and methodological materials of the VVIA. Moscow, 1995. (in Russian)

7. Interstate Aviation Committee / Investigation of aviation accidents and incidents. Available at: https://mak-iac.org/rassledovaniya / (accessed 23 November 2025). (in Russian)

8. Komov А. А. (2016). Assessment of PD-14 engines protection from damages in MS-21 plane. Izvestia of Samara Scientific Center of the Russian Academy of Sciences. 18(4-3): 586-591. (in Russian)

9. Motycka D. L. (1975). Ground Vortex-Limit to Engine. Reverser Operation. 1975.

10. Report on the results of the investigation of the aviation incident with the RRJ-95B RA-89112 aircraft. Moscow: AMRIPP Rosaviatsia, 2020. 104 p. (in Russian)

11. Rodert L. A., Garret F. B. (1955). Ingestion of Foreign Objects into Turbine Engines by Vortices. Washington: NACA. Technical note 3330, 1955. 23 p.

12. Shanyavskiy A. A. (2007). Modeling of fatigue fractures of metals. Ufa: Monograph, 2007. 498 p. (Synergy in aviation). (in Russian)

13. The ARMS methodology for assessing operational risks in aviation organizations (2010) / Developed by the ARMS working group, 2007-2010. Available at: https://helicopter.su/assets/media_sources/ehest-ihts/2016/ARMS/2%20-%20SMS%20-%20ARMS_Translation_RU.pdf (accessed 20 November 2025). (in Russian)

14. The Human Factors «Dirty Dozen»: Electronic Library «SkyBrary». Available at: https://skybrary.aero/articles/human-factors-dirty-dozen (accessed 18 October 2025).