Sepahan A140 at Tehran on Aug 10th 2014, lost height after takeoff due to engine failure

Last Update: November 9, 2017 / 20:13:42 GMT/Zulu time

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Incident Facts

Date of incident
Aug 10, 2014

Classification
Crash

Flight number
SPN-5915

Destination
Tabas, Iran

Aircraft Registration
EP-GPA

Aircraft Type
Antonov An-140

ICAO Type Designator
A140

A Sepahan Airlines Hesa IrAn-140-100, registration EP-GPA performing flight SPN-5915 from Tehran Mehrabad to Tabas (Iran) with 42 passengers and 6 crew, departed Tehran Mehrabad Airport's runway 29L when the aircraft lost height and crashed into a residential area near the Liberty/Azadi Stadium about 1.6km/0.85nm northwest of the runway end at about 09:18L (04:48Z), the tail of the aircraft, the only still recognizable part, came to rest at approximate position N35.7074 E51.2850. 11 occuptants were taken to hospitals with serious injuries, 37 occupants died in the crash. There were no injuries or casualties on the ground. 3 passengers later died in hospital care, 34 passengers and all 6 crew perished as result of the crash, 8 passenges survived with serious injuries.

Emergency services reported all bodies have been recovered and have been taken to the coroner's office. 5 occupants rescued alive succumbed to their injuries on their way to the hospital. The post impact fire was extinguished about 90 minutes after the crash.

Air Traffic Control reported the aircraft was climbing in a westerly direction when the crew reported a problem and requested to turn right instead of turning left by standard departure procedures, then went down.

The airline reported the aircraft suffered a technical malfunction of the left hand engine (Klimov TV3) while on a charter flight. The aircraft had last flown two days earlier.

While Iranian officials state that all on board perished and there were no injuries on the ground, Iranian media report between 3 and 10 people being treated in hospitals for severe burns related to the crash.

In the afternoon Iran's Civil Aviation Organisation (CAO) reported that 37 occupants of the aircraft died in the crash, 11 were taken to hospitals. An investigation commission has been formed, the black boxes were recovered and delivered to the investigation commission.

On Aug 11th 2014 survivors reported that the right hand propeller/engine stopped.

Pending investigation the Iranian government has grounded all IrAn-140s.

On Sep 3rd 2014 Iran's Ministry of Transport reported that the recordings of cockpit voice and flight data recorder have been read out and analysis and discussion of the data has begun. The investigation board decided during their 8th session that fatigue testing of aircraft parts and equipment as well as metallurgical analysis of molecular structures is to be conducted.

On Oct 6th 2014 Iran's Ministry of Transport reported that according to initial analysis of the facts collected so far the probable causes of the crash were a combination of environmental, technical and human factors surrounding the shut down of an engine. The final report is being drafted.

On Oct 6th 2014 Iran's media report citing remarks of the chair of Iran's Civil Aviation Authority in a press conference, that the ministry had become aware of one engine shut down and two more engine problems in October 2013 that according to an expert commission, with engine experts of Antonov participating, had to be attributed to environmental factors with ambient temperatures exceeding +30 degrees C and the engine's fuel system unable to control temperatures in such conditions and moist contained in the fuel causing substantial corrosion internal of the engine in such environment. As result the Ministry pushed to restrict the certification of the Hesa IrAn-140 to operation below 30 degrees C ambient temperature, however, the experts of Hesa and the operator argued that the claims by the expert commission were entirely irrational and insisted that the flights needed to continue. The aircraft continued operations.

A Hesa IrAn-140 is a licensed version of the Antonov AN-140 produced by Hesa in Iran.

Iran's CAO released their final report concluding the probable causes of the crash were:

The accident investigation team determined that the main cause of this accident was combination of:

1. Electronic engine control (SAY-2000) failure simultaneously with engine No: 2 shutdown, just about 2 seconds before aircraft lift-off.

2. AFM Confusing performance chart resulted the pilots relying on performance calculation that, significantly over-estimate the aircraft MTOM.

Contributing Factors to the accident were:

1. Aircraft flight manual unclear procedure, including the procedure for calculating maximum allowable take-off weight, VR and V2 and ambiguity in the climb segment definition and applications.

2. Crew performance, including:

- PIC rotated the aircraft at the speed of about 219 km/h (whereas 224 km/h is the speed recommended by the AFM table 4.2.3)

- The crew failed to perform the manual propeller feathering procedure for the failed engine.

- The PIC's decision to fly with the aircraft, notwithstanding, had about 190 kgf overweight.

-  Aircraft fuel was about 500 kg more than required fuel for the accident flight.

- The appearance of negative thrust from the unfeathered propeller blades at takeoff were not considered during the aircraft certification tests, as it was considered improbable. However, in the accident flight the negative thrust did appear and affected the flight performance.

The captain (63, ATPL, 9,478 hours total, 2,000 hours on type) was pilot flying, the first officer (32, CPL, 572 hours total, 400 hours on type) was pilot monitoring.

The captain performed the load computations based on the flight crew operating manual. The aircraft departed with a takeoff mass of 19866kg, about 190kg above maximum takeoff weight permitted for the present weather conditions according to the graphs used in the FCOM (in the analysis the CAO determined that the maximum takeoff mass should have been computed at 17,200 kg and the aircraft actually took off 2666kg overweight). According to the FCOM the Vr and V1 was thus determined to be 224kph (121 KIAS), V2 was determined at 234kph (126 KIAS).

Due to limitations with flaps 15 the captain decided to use flaps 10 for departure. The CAO reported that there was no Standard Operating Procedure for takeoff with flaps 10 in case of an engine failure. The captain did not set the trim tab into the takeoff range (0-6 degrees) but left it at -2 degrees, also the rudder trim was not set to neutral leaving it at -3 degrees.

The aircraft accelerated for takeoff from Mehradbad's runway 29L, ambient temperatures was +35 degrees C at 1208 meters MSL, when about 2 seconds prior to rotation the right hand engine failed, however, the according warnings did not activate, the propeller blades turned to 46 degrees and stopped subsequently producing significant drag. The captain continued the takeoff and rotated the aircraft at 219 kph (instead of 224 kph), 4 seconds after the engine failure the crew began to discuss the engine failure, 9 seconds after the failure the first officer reemphasized the right hand engine had failed. However, neither pilot pushed the button to turn the right hand engine off and feather the propeller. About 14 seconds after the engine failure the crew communicated the engine failure to ATC. In the meantime the airspeed, that had peaked at 224 kph shortly after becoming airborne began to drop through 181 kph (98 KIAS). The aircraft stalled and impacted ground.

The aircraft turned gradually right, reached a maximum height of 40 meters and impacted ground at a highway and into the SAMT Industrial Complex.

The CAO analysed that the electronic engine control malfunctioned just prior to the engine failure causing the fuel supply to the engine to be cut off, although otherwise the fuel supply system remained functional. The propeller blades began to turn and reached 46 degrees, then stopped. Due to the malfunction, that lasted for 17 seconds, the EEC did not command the shut down of the engine or the feathering of the propeller as designed, too. Only 17 seconds after the engine failure the commands to shut the engine down and feather the propeller occurred, the propeller turned into its feathered position. The causes of the EEC malfunction could not be determined.

The CAO analysed that although the relevant engine failure warnings did not occur the crew detected the engine failure within 5 seconds after the failure, the warnings occurred only 14 seconds later.

The CAO analysed with respect to the aircraft documentation, in particular maximum takeoff mass tables and graphs: "The accident investigation team revealed that AFM procedure for weight calculation is not clear that confused the crew. So if for accident flight, charts of AFM section 7.2 page17 (Fig 7.2-1B) and Page 18 (Fig 7.2-1r) are used, the aircraft weight (19866 kgf) will be outside of graph limits. By using this graph the maximum allowable weight, VR and V2 respectively will be 18850 kgf, 223 km/h and 226 km/h. So gained results have significant difference with result taken from chart of AFM Fig.7.2-11 and table 4.2.3. By considering the ground speed limitations at take-off, in accordance with the An-140-100 AFM charts (Section 7.2.2) the calculated MTOW should have been 17200 kgf. Therefore according to aforementioned findings the AFM procedure for takeoff weight calculation was not clear and confused the crew."

The CAO analysed that even if the engine warnings had worked and the crew had performed according to standard operating procedures, the aircraft would not have complied with the airworthiness requirements and would not have reached V2 before climbing through 10.7m (35 feet AGL).

The CAO reported that a study into previous A140 occurrences revealed that the EEC SAY-2000 produced an engine failure rate that was above acceptable levels. The CAO wrote: "The study revealed that designer performed some modification and software improvement to rectify the malfunction, especially for SAY-2000 malfunction, but the failure rate of these systems was not reduced to acceptable levels."

Metars:
OIII 100600Z 10010KT 9999 FEW040 SCT100 37/M04 Q1013 A2993 NOSIG
OIII 100530Z 09010KT 9999 FEW040 SCT100 37/M03 Q1013 A2993 NOSIG
OIII 100500Z 07008KT 9999 FEW040 SCT100 36/M02 Q1013 A2992 NOSIG
OIII 100430Z 06010KT CAVOK 35/M02 Q1013 A2992 NOSIG
OIII 100400Z 07006KT CAVOK 34/M03 Q1013 A2992 NOSIG
OIII 100330Z 07008KT CAVOK 33/M02 Q1013 A2991 NOSIG
OIII 100300Z 08006KT CAVOK 32/M01 Q1012 A2991 NOSIG
OIII 100230Z 08006KT CAVOK 32/M02 Q1012 A2990 NOSIG
OIII 100200Z 06008KT CAVOK 32/M02 Q1012 A2989 NOSIG
OIII 100130Z 09006KT CAVOK 32/M02 Q1011 A2988 NOSIG
OIII 100100Z 06010KT CAVOK 32/M03 Q1011 A2988 NOSIG
OIII 100030Z 06006KT CAVOK 32/M02 Q1011 A2988 NOSIG
OIII 100000Z 05008KT CAVOK 32/M03 Q1011 A2988 NOSIG
Incident Facts

Date of incident
Aug 10, 2014

Classification
Crash

Flight number
SPN-5915

Destination
Tabas, Iran

Aircraft Registration
EP-GPA

Aircraft Type
Antonov An-140

ICAO Type Designator
A140

This article is published under license from Avherald.com. © of text by Avherald.com.
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