Incident
On January 11, 2008, an Airborne Express Inc. Canadair CL-600 aircraft, registration N-601JM, departed Budapest-Ferihegy Airport on a scheduled flight to Milan. During the initial climb, after lift-off, the landing gear did not retract as commanded. The flight crew detected the anomaly and decided to return to Ferihegy, where the aircraft landed without further incident.
Investigation
The Hungarian Transportation Safety Bureau (KBSZ) conducted a simplified investigation into the occurrence. According to information obtained by the organization, the gear retraction problem was caused by a faulty proximity sensor on the left main landing gear. This sensor also governs the sequencing of the gear retraction process. As a result of the malfunction, the retraction cycle did not complete.
Resolution
Technical personnel from the aircraft owner cleaned the suspect sensor and performed a gear swing test after jacking the aircraft. However, the test was unsuccessful, and the central fault display unit indicated a sensor fault. The following day, a replacement sensor arrived from Vienna and was installed. After the replacement, the fault no longer appeared, and the aircraft subsequently departed in a serviceable condition.
Conclusion
The KBSZ considered the case closed based on the information available. No safety recommendations were issued, as the investigation board did not identify any circumstances warranting such recommendations.