N4167GCessna 402B · 1976

On July 11, 2024, about 0923 Atlantic standard time, a Cessna 402B airplane, N4167G, was destroyed when was involved in an accident near the Rafael Hernandez Airport (BQN), Aguadilla, Puerto Rico. The private pilot was fatally injured, and a person on the ground sustained minor injuries. The airplane was operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight.

According to a mechanic who assisted the pilot with his preflight inspection, the pilot planned to complete the flight from his home airport, BQN, to Luis Munoz Marin International Airport (SJU), San Juan, Puerto Rico, where he planned to have several maintenance discrepancies addressed. The mechanic reported that the four fuel tanks were found near empty or about one-third full during the preflight inspection. A fuel receipt showed that the pilot purchased 13 gallons of 100LL AvGas before the accident flight.

The mechanic reported that, after the fuel was added, the left main fuel tank contained about 15 gallons and the right main fuel tank contained about 6-8 gallons. He estimated that the left auxiliary tank contained about 20 gallons and the right auxiliary tank contained about 15 gallons. He did not observe the pilot sump the fuel tanks during the preflight inspection and the correct fuel measuring dip stick was not present with the airplane. He reported that the pilot told him that he planned to use the main tanks for takeoff and then the auxiliary tanks while enroute.

The mechanic observed the pilot start the engines and complete a normal engine run-up, but did not witness the airplane take off.

FAA ADS-B data showed that the airplane departed runway 8 and climbed to about 1,500 ft mean sea level (msl) about 2 miles east of the approach end of runway 8. The airplane then made a turn to the left and began a descent. When the airplane reached about one mile northeast of the airport, the track turned directly toward the approach end of runway 26. In the final 30 seconds of track data, the altitude and groundspeed continued to decrease rapidly. The final track data point showed the airplane about .3 miles northeast of the runway 26 threshold at 200 ft msl and 73 knots groundspeed, on a heading of 209°.

Review of FAA air traffic control (ATC) ground and tower communications found that about 0914 the pilot requested a visual flight rules (VFR) departure to the east and about 3 minutes later was cleared for takeoff from runway 8. At 0921:31, the pilot called the tower and stated, “yeah going back to runway 8 I just wanna check the uh vibration on the right engine uh uh no emergency for right now for 1 6 7 gulf” (see figure). The controller immediately cleared the pilot to enter the left downwind for runway 8 and provided him with the current weather and airport information. At 0922:25, the pilot stated “aguadilla ground mayday mayday I I engine failure I will use the other side of the runway for 1 6 7 gulf.” The controller immediately cleared the pilot to land on runway 26 and provided him the current wind information of 090° at 10 kts, gusting to 14 kts. The pilot read back cleared to land and there were no further communications.

Figure: Overview of the airplane's flight path and excerpts of the pilot's communication with the ATC tower

Two air traffic controllers observed the airplane’s flight path as it was flying directly toward the runway 26 threshold. They observed the airplane in its final few seconds of flight abruptly roll to the right and descend vertically into terrain. Before the descent, one controller reported that he did not observe anything abnormal about the airplane. Surveillance video captured the final few seconds of flight, which showed the airplane in a steep vertical descent and right roll with the landing gear retracted. After impact, an explosion and postaccident fire were observed.

The airplane’s maintenance records included an annual inspection maintenance endorsement, dated April 24, 2024 (about 11 weeks before the accident), which denoted that the airplane was “UNAIRWORTHY.” Attached to the endorsement was a discrepancy sheet that had 3 pages of items to be corrected, including discrepancies with both engines and the airframe. Some items annotated on the discrepancy sheet included left and right fuel tank caps that required replacement (annotated “Done”), one of the right engine’s cylinders below a compression of 45 psi, all right engine’s spark plugs needing replacement, the right engine’s oil and oil filter needing replacement, the right engine’s fuel filter needing replacement, the right engine’s and oil an fuel lines needing replacement (due to time in service and date).

The airplane had not been signed off for an annual or 100-hr inspection after the April 11, 2024, inspection. According to the mechanic who wrote the list, the majority of the items had not been corrected. This mechanic advised the pilot that he needed to apply for a ferry permit from the FAA in order to complete the flight to SJU. No documentation was available showing that the pilot had ferry permit had been obtained prior to the accident flight.

From November 2020 to April 2024, the maintenance records showed that the airplane had flown 1.4 hours. The most recent annual/100-hr inspection endorsement that found the airplane in an airworthy condition was dated June 6, 2019. The maintenance records indicated that the left engine was overhauled on December 14, 2011, and the right engine was field overhauled on October 24, 2008. According to the current revision of Continental Motors Service Information Letter SIL98-9, the recommended engine time between overhaul for the TSIO-520-E engine was 1,400 hours or 12 years, whichever occured first. As of November 2020, the left engine had accumulated 400.3 hours since overhaul. As of June 2019, the right engine had accumulated 1,400.0 hours since overhaul.

According to FAA records, the airplane was purchased by the registered owner in August 2016.

The airplane’s maintenance records included an annual inspection maintenance endorsement, dated April 24, 2024 (about 11 weeks before the accident), which denoted that the airplane was “UNAIRWORTHY.” Attached to the endorsement was a discrepancy sheet that had 3 pages of items to be corrected, including discrepancies with both engines and the airframe. Some items annotated on the discrepancy sheet included left and right fuel tank caps that required replacement (annotated “Done”), one of the right engine’s cylinders below a compression of 45 psi, all right engine’s spark plugs needing replacement, the right engine’s oil and oil filter needing replacement, the right engine’s fuel filter needing replacement, the right engine’s and oil an fuel lines needing replacement (due to time in service and date).

The airplane had not been signed off for an annual or 100-hr inspection after the April 11, 2024, inspection. According to the mechanic who wrote the list, the majority of the items had not been corrected. This mechanic advised the pilot that he needed to apply for a ferry permit from the FAA in order to complete the flight to SJU. No documentation was available showing that the pilot had ferry permit had been obtained prior to the accident flight.

From November 2020 to April 2024, the maintenance records showed that the airplane had flown 1.4 hours. The most recent annual/100-hr inspection endorsement that found the airplane in an airworthy condition was dated June 6, 2019. The maintenance records indicated that the left engine was overhauled on December 14, 2011, and the right engine was field overhauled on October 24, 2008. According to the current revision of Continental Motors Service Information Letter SIL98-9, the recommended engine time between overhaul for the TSIO-520-E engine was 1,400 hours or 12 years, whichever occured first. As of November 2020, the left engine had accumulated 400.3 hours since overhaul. As of June 2019, the right engine had accumulated 1,400.0 hours since overhaul.

According to FAA records, the airplane was purchased by the registered owner in August 2016.

The airplane impacted a residential area front yard including trees, powerlines, and propane fuel tanks. The wreckage remained in a compact area and was oriented on a magnetic heading of 330°. A postaccident fire consumed a majority of the cockpit, fuselage, and portions of both wings.

Flight control cable continuity was established from the elevator, rudder, and elevator and rudder trim tabs to the fire damaged cockpit. The elevator trim was found about 1.5°- 2.5° down. The aileron control cables from the cockpit to the center sector were continuous. The right aileron was attached to the remaining wing section and cable continuity was established to the center sector. The left aileron was completely thermally destroyed and unobserved. The left aileron main cables were found attached to the wing sector and continuous to the center sector. Left aileron trim cable continuity was established from the actuator to the control wheel. The chain at both ends was disconnected from their respective sprocket. The flap panels were thermally destroyed and not observed. The measurement of the chain on the actuator corresponded to a flap position of about 10°. The flap cables were continuous to the drive bellcranks and outboard pushrods. The landing gear were found retracted. The flap actuator was measured and corresponded to about a 10° position. The majority of the fuel tanks were thermally damaged. The fuel selector panel was thermally destroyed and the selector valves did not reveal reliable indications. The cockpit, switches, levers, and flight instruments were all severely damaged by fire.

Both engines had separated from the airframe and were found a few feet forward of the wings. The engines exhibited impact and post-impact fire damage. The engine casings did not have any large cracks or holes. The spark plugs and magnetos for each engine remained securely installed. Each engine was equipped with a three-blade propeller.

Two of the left engine propeller blades exhibited little to no torsional twisting or bending. One blade exhibited aft bending near its tip, and also had chordwise scratches near the blade root.

The right engine propeller blades exhibited varying degrees of chordwise scratching and blade polishing. One blade displayed aft bending, and one blade exhibited forward bending near its tip. The remaining blade exhibited little forward or aft bending.

During an examination at the engine manufacturer’s facility, the right engine crankshaft rotated 720° when force was applied to the crankshaft flange. Cylinder compression and valve action movement were observed on all cylinders. Both magneto condensers were damaged by thermal forces and each of the magnetos produced blue spark when a replacement condenser was supplied. The fuel manifold was damaged by thermal forces and was opened for further investigation. Visible corrosion and remains of diaphragm material were present. Below the fuel screen at the fuel inlet within the manifold was a large quantity of debris and foreign material.

The left engine crankshaft rotated 720° when force was applied to the crankshaft flange. Cylinder compression was observed on cylinder Nos. 2 through 6. Compression could not be obtained on cylinder No. 1 and when compressed air was applied it leaked past the piston rings. Valve action movement was observed on all cylinders.

According to the Cessna Model 402B Pilot’s Operating Handbook (POH), section 3, “Emergency Procedures,” the recommended safe single-engine speed was 91 knots indicated air speed (KIAS). The minimum controllable airspeed was listed as 82 KIAS.

Furthermore, the POH procedure Engine Failure After Takeoff (Speed Above 91 KIAS with Gear Up or In Transit) listed the following as “immediate action items” that “should be committed to memory”:

1. Mixtures – FULL RICH

2. Propellers – FULL FORWARD

3. Throttles – FULL FORWARD (34.5 Inches Hg.)

4. Landing gear – CHECK UP

5. Inoperative engine:

a. Throttle – CLOSE

b. Mixture – IDLE CUT-OFF

c. Propeller – FEATHER.

It then stated to establish a bank of 5° toward the operative engine.

One person on the ground, who was riding his bicycle near the road the airplane impacted, sustained minor injuries when he was struck with small debris and fell off his bicycle.

According to the autopsy report issued by the Instituto de Ciencias Forenses, Gobierno de Puerto Rico, the cause of death was thermal injuries, and the manner of death was an accident.

The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem specimens from the pilot. No tested-for substances were detected.