What happened
On June 6, 2016, a Piper PA-31, registration PT-CKW, was conducting an aerial survey flight near Juazeiro do Norte, Brazil. The flight, operated by Aeroimagem S.A. Engenharia e Aerolevantamento, included a pilot and an equipment operator. During the traffic pattern while performing landing checks, the crew discovered that the landing gear extension cycle had failed to complete.
The pilot remained in the holding pattern for approximately one hour and 4 empyty minutes, attempting to deploy the gear using both the normal and emergency systems, without success. Ultimately, the pilot performed a landing with the landing gear retracted. The aircraft traveled approximately 200 meters along the runway before coming to a stop. The impact resulted in substantial damage to the propellers, lower antennas, and the underside of the fuselage, though both occupants were uninjured.
The investigation
CENIPA investigators examined the aircraft and identified a hydraulic fluid leak originating from a pressure line hose (P/N 17766-2) responsible for extending the left main landing gear. The investigation revealed that the hose, which had been in service since 1969 and had accumulated 7,342.5 flight hours, showed significant signs of deterioration, including exposed steel braiding, abrasion marks, elastomer drying, and corrosion.
Investigators also reviewed maintenance records. While a 100-hour inspection had been completed six days prior to the accident, the documentation lacked the required inspector's signature and formal approval for return to service. Furthermore, a previous 50-hour inspection had been performed by a mechanic whose certification was limited to the powerplant group, rather than the airframe.
Findings
- The failure of the hydraulic hose (P/N 17766-2) caused a loss of hydraulic fluid, which prevented the landing gear from extending via both normal and emergency modes.
- The hydraulic hose was in a highly deteriorated state, with visible corrosion and structural degradation.
- Maintenance failures and inadequate oversight of the aircraft's maintenance program contributed to the incident.
- The location of the hose made full visual inspection difficult, potentially compromising the quality of previous inspections.
- There was a lack of proper administrative oversight regarding maintenance signatures and the specific qualifications of the personnel performing inspections.