Mandalay E145 at Sittwe on Sep 18th 2017, hard landing accident cracks wing spar, aircraft operated three more sectors

Last Update: April 15, 2018 / 12:57:05 GMT/Zulu time

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Incident Facts

Date of incident
Sep 18, 2017

Classification
Report

Destination
Sittwe, Myanmar

Aircraft Registration
XY-ALE

Aircraft Type
Embraer ERJ-145

ICAO Type Designator
E145

An Air Mandalay Embraer ERJ-145, registration XY-ALE performing a scheduled flight from Yangon to Sittwe (Myanmar) with 36 passengers and 4 crew, landed on Sittwe's runway 11 but touched down hard at +4.226G vertical acceleration. The aircraft rolled out and taxied to the apron. There were no injuries.

The first officer subsequently performed a walk around but, according to him, did not detect any anomaly. The aircraft departed for the return flight and subsequently flew another rotation before daily maintenance was carried out, during which mechanics found substantial damage including a cracked wing spar and removed the aircraft from service.

Myanmar's Aircraft Accident Investigation Bureau (MAAIB) released their final report concluding the probable cause of the accident was:

The pilot continued to landing during an unstabilized approach.

The MAAIB reported: "Flight crew did not entry hard landing or suspected hard landing in the technical log and did not report about it to anybody. That's why maintenance engineers were not able to perform thorough hard landing inspection. It was discovered that there was no hard landing monitoring system."

The MAAIB reported the captain (62, ATPL, 17,878 hours total, 1,151 hours on type) was pilot flying, the first officer (39, ATPL, 3,596 hours total, 1,002 hours on type) was pilot monitoring.

The MAAIB did not report what type of approach was flown in the factual section, in the analysis section the MAAIB reported a visual approach was flown. The MAAIB stated, that the aircraft intercepted the final approach course at 132 KIAS at 942 AGL and was descending at about 500 fpm. At 500 feet AGL the aircraft levelled off. 0.8nm before the runway threshold the autopilot was disconnected at 138 KIAS and at 520 feet AGL, the thrust levers were slowly moved towards their idle positions. The vertical descent rate began to gradually increase and reached 1300 fpm at 347 feet height, IAS was 134 knots. At 249 feet AGL a master caution, probably related to an EGPWS warning, activated, the vertical descent rate had reached 1429 fpm. The aircraft touched down, the FDR initially recorded +1.1G, the next sample 1/8 seconds later showed +4.226G, the MAAIB annotated the actual vertical acceleration might have even exceeded that value.

The MAAIB then wrote:

After the landing in Sittwe Airport, the First Officer performed a transit check which required him to visually inspect the aircraft to ensure that there was no anomaly that affect the aircraft¡¦s airworthiness for the next flight. According to him, he did not observe any anomaly during the transit check.

The aircraft performed two further flights before the operator¡¦s maintenance personnel performed night stop inspection of the aircraft at Yangon Airport, after all scheduled flights for that aircraft was completed. During the night stop inspection, the maintenance personnel discovered several cracks in the aircraft¡¦s right wing area.

The MAAIB listed following damage:

1.3.1 Right Hand Wing, Spar No 3 broken
(a) Crack propagation from (RIB 3A YA-1392.67 up to RIB 5 YA-2222.70)
(b) Length of crack is 32 inches.
(c) Nature of crack is diagonal across the SPAR No 3
1.3.2 RIB 4A twisted or deformed
(a) The length twist is about 9 cm
1.3.3 Right Hand Wing Skin at Trailing Edge Separation
(a) Location is between Y¡V1085.00 to RIB 4A YA-1912.56
(b) Fasteners to RIB 3 and Spar No 3 went off
(c) Length of Skin Separation (61 cm long).
(d) Peak of buckle is about 3 cm high.
1.3.4 Buckling of Right Hand Wing Inboard Spoiler
(a) Spoiler Panel buckling (Length is about 128 cm in wave form)
1.3.5 Deformation of LH Side lateral fairing, (Location: Central Fuselage)
(a) Fiber glass panel buckled (Length 180 cm)
1.3.6 Deformation of RH Side lateral fairing, (Location: Central Fuselage)
(a) Fiber glass panel buckled (Length is 190 cm)

The MAAIB reported the weather: "Visual observation by the air traffic controller was: wind 180ƒA at 10 knots, sometimes gusty wind at 20 knots. It was raining."

The MAAIB analysed:

The aircraft was making visual approach to runway-11 of the Sittwe airport. The aircraft height when intercepting and when established in the final approach course were significantly lower than that instructed by the IAC. The crew then flew the aircraft to a height of approximately 500 ft, which is consistent with obstacle clearance height of the NDB procedure to runway 11 and leveled off until 0.8 nautical mile from the runway threshold.

At 0.8 nautical mile from the runway 11 threshold and at a height of 520 ft AGL, the autopilot was disengaged the aircraft resumed the descent, with vertical speeds exceeding -1400 fpm at some points and engines¡¦ power gradually brought to IDLE. The fact that the crew leveled off and maintained the aircraft in an altitude consistent with the obstacle clearance height suggests that they did not have the runway in sight until at least 0.8 nautical mile from the runway threshold, what seems to indicate that restrict visibility conditions prevailed. According to the Embraer ERJ-145 SOP (section 3-40, page 1, see Annex C), during approaches in IMC (which seems to be the case for this landing), the airplane must be stabilized by 1000 ft from touchdown. An approach is considered stabilized when all of the following criteria are met:

- The airplane is on the correct flight path;
- Only small changes in heading/pitch are required to maintain the correct flight path;
- The airplane is in the correct approach speed;
- The airplane is in the correct landing configuration;
- Sink rate is not greater than 1000 ft per minute; if an approach requires a sink rate greater than - 1000 ft per minute, a special briefing should be conducted;
- Power setting is appropriate for the airplane configuration;
- All briefings and checklists have been conducted.

The aircraft was only stablished on the final correct flight path below 1000 ft (the aircraft was established on final approach course about 700 ft AGL) and its sink rate exceeded 1400 fpm during the short final, period during which the TLAs were brought to idle. Therefore, an analysis of this approach indicates that it was not stabilized. Still according to the ERJ-145 SOP, ¡§unstable approaches may result in difficult landings with unexpected sink rates, side loads or bounce backs¡¨.
Incident Facts

Date of incident
Sep 18, 2017

Classification
Report

Destination
Sittwe, Myanmar

Aircraft Registration
XY-ALE

Aircraft Type
Embraer ERJ-145

ICAO Type Designator
E145

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