The Aviation Safety Council （ASC） releases final report on the investigation of a National Airborne Service Corps, Ministry of the Interior （NASC） Beech Super King Air 350 aircraft, number NA-302, landing gears retracted and forcing the aircraft to slide on its belly causing aircraft damage during landing at Taichung/Ching-chuan-kang Airport （CCK Airport）.

On November 7, 2015 around 1310, the aircraft completed its aerial photographic mission and returned to CCK Airport. Due to the 2-ampere circuit breaker which controls power source for the landing gear popped out, electricity for the power pack was cut off so the motor could not operate to build up pressure during aircraft landing. The flight crew erroneously judged the landing gear not down and lock indication light and warning sound were false alarm. Instead of executing the manual extension procedure as required by the operation manual to lower and down lock the landing gear, the flight crew decided to land anyway. This resulted in landing gears retracted upon touching ground and causing the aircraft landed on its belly that damaged to the aircraft. All 4 people on board were safe.

Pursuant to the Aviation Occurrence Investigation Act of the Republic of China and, referring to Annex 13 to the Convention on International Civil Aviation, the ASC, an independent aviation occurrence investigation agency, started the investigation. The organization or agency been invited to join the investigation team included: Air Force Command Headquarters of the Ministry of National Defence, NASC, Aerospace Industrial Development Corporation and National Transport Safety Board of the USA.

The 'Draft Investigation Report' of the occurrence was first reviewed and approved by the ASC's 47th Board meeting on July 26, 2016. This Report was sent to relevant agencies for comments. Upon compilation and integration of comments and suggestions, this Report was finally approved as amended on October 25, 2016 by the 50th Board meeting of the ASC.

Based upon the factual information gathered during the investigation process and the results of analysis, 19 findings were obtained and 9 safety recommendations for improvements were issued as follows.

Findings related to probable causes:

1. The 2-ampere circuit breaker which controls power source for the landing gear popped up after the occurrence aircraft having landed shows that electricity for the power pack was cut off when the aircraft was in the process of landing, so the motor could not operate to build up pressure.
2. When the occurrence aircraft was landing the first time, abnormal status of the indicating light for the landing gear down-and-locked was already existed. It was possible that the 2-ampere circuit breaker which controls the power for power pack of the landing gear had popped up before the first landing attempt, thus incapacitating the hydraulic system, rendering it impossible to build up necessary pressure for operating the landing gear. The subsequent two more operations by the flight crew to lower and down lock the landing gear also failed due to insufficient pressure within the landing gear system.
3. During the occurrence aircraft landing, the landing gear not down and lock indication and warning sound came out when the flight crew extended the landing gear and flaps. The flight crew erroneously judged the not down and lock indication and warning were false alarm. Instead of executing the manual extension procedure as required by the operation manual to lower and down lock the landing gear, the flight crew decided to land anyway. The heavy weight of the aircraft causing all landing gear to retract upon touching ground and causing the aircraft landed on its belly.

Findings related to the risks:

1. The occurrence flight crew was not sufficiently knowledgeable about the landing gear and warning system of this type of aircraft; thus affecting the judgment of the flight crew when facing a situation of abnormal indication about the landing gear.
2. The crew resources management among the occurrence flight crew, including their judgment about abnormal condition of landing gear, their awareness level of possible impact of such situation upon aviation safety, and the discussion among the crew, failed to show full crew communication and effective decision-making as a team. At a critical moment when facing abnormal landing gear indication, judgment by the flight crew on how to handle this situation will be very much affected.
3. During the occurrence, the check pilot might have, from his previous personal experience in the encountering of landing gear indication light off, ignored or refused to believe the information then present, which was inconsistent with his expectations, thereby influencing his judgment about the condition of landing gear.
4. The flight crew did not perform the pre-landing check during the landing process by complying with Flight Operations Management Manual and the check procedure for this particular type of aircraft.
5. Training programs for new recruited pilot in the fixed wing fleet of NASC were not sufficient to achieve the objects and purposes required for the pilots in terms of subject-teaching and practical training. Without clear-cut course for crew resources management, the current training programs will not be able to familiarize the flight crew with functions of various systems and operational procedures.
6. Regular yearly training for the fixed wing fleet of NASC offered teaching programs and practical training for operations regarding landing gear; but it did not offer detailed training programs for related systems and abnormal/emergency procedures, there was no record of implementation of such programs, nor had any training for manual operation of landing gear been conducted. This occurrence shows that the flight crew did not sufficiently understand the landing gear system, and that their regular yearly training had not yet shown the results.
7. Mission Performance Procedures and the current Operation Manual of NASC were without comprehensive standard operation procedure, this is not helpful to the flight crew in their routine operation and their handling of abnormal/emergency situations.
8. The manpower shortage of flight instructors and insufficient training resources for the fixed wing fleet of NASC might impact upon not only the operations of fixed wing fleet but also the training result and the performance of their missions.

Safety Recommendations

To the National Airborne Service Corps, Ministry of the Interior

1. Require flight crew to follow Flight Operations Management Manual and Aircraft Operation Manual in carrying out the related inspections required; when encountering abnormal circumstances during flight, they should also follow Aircraft Operation Manual in handling the situations and making judgments over the contingency.
2. Check the contents of training programs for new recruited pilot of fixed wing fleet in terms of the subjects taught and practical work; planning the contents of difference training for B350 and B200 aircraft models; and explicit training for crew resources management should be in place.
3. Improve flight crew's aircraft system knowledge to facilitate the handling of abnormal situations during flight.
4. Emphasize crew resources management training to keep the flight crew's teamwork spirit intact and to ensure effective communication and decision-making among them.
5. Check regular yearly training method and validation of pilot certificate for flight crew of fixed wing fleet and differentiate between B350 and B200 aircraft types. In addition, such training should include thorough program for abnormal/emergency landing procedure, specialized subjects on flight, and the implementation process of such training should be meticulously recorded.
6. Stipulate a comprehensive standard operation procedure and made known to all the flight crew, this will be conducive to normal operation by flight crew and to the handling of abnormal/emergency circumstances.
7. Check human resources and training resources for check pilot and assess fleet renewal plan of fixed wing fleet to facilitate flight crew's training, examination and the execution of mission.
8. Implement dynamic audit of fixed wing fleet to ensure discovery of any training deficiency in time.
9. Evaluate the feasibility of equipping the aircraft with flight data recorder or, alternatively, simplified flight recording device.

Full investigation report is available for download at  http://www.asc.gov.tw

Sherry Liu, Engineer
Tel: 02-89127388-ext330
 Email:sherry@asc.gov.tw