Sriwijaya B735 at Jakarta on Jan 9th 2021, lost height and impacted Java Sea
Last Update: May 18, 2021 / 19:17:43 GMT/Zulu time
The FAA argued:
The FAA previously issued AD 2000-23-34, Amendment 39-12007 (65 FR 75595, December 4, 2000) (AD 2000-23-34), which applies to all Boeing Model 737-300, -400, and -500 series airplanes, and requires replacing the existing A/T computer with a new, improved A/T computer that included an asymmetric cruise thrust monitor.
On January 9, 2021, a Model 737-500 series airplane operated by Sriwijaya Air was involved in an accident on a flight from Jakarta, Indonesia. There were 62 fatalities. During the ongoing accident investigation, Boeing reported that a flap synchro wire failure may go undetected by the A/T computer on the affected airplanes. Further investigation has revealed that the design update for the A/T computer required by AD 2000-23-34 does not properly account for a possible latent failure of the flap position sensor, which is one data component needed to provide the logic necessary for the asymmetric cruise thrust monitor to operate. Failure of the asymmetric cruise thrust monitor to engage during a large thrust asymmetry event could result in loss of control of the airplane. At this time, the preliminary data of the ongoing accident investigation shows that it is highly unlikely that the accident resulted from the latent failure of the flap synchro wire. However, the FAA has determined that the unsafe condition identified in this AD could exist or develop in Model 737-300, -400, and -500 series airplanes, and that this AD is therefore necessary to address the identified unsafe condition.
The FAA has confirmed that accomplishment of the applicable BITE test in the existing airplane maintenance manual (AMM) detects the flap synchro wire failure. This test is currently not required to be performed repetitively, leading to a potential latent failure if the test is not performed regularly, which will be required by this AD.
Model 737-100 and -200 series airplanes are not affected by this AD due to an A/T design difference that is not subject to the identified unsafe condition.
The AD requires operators to conduct:
Within 250 flight hours or 2 months after the effective date of this AD, whichever occurs first: Perform the applicable A/T computer BITE (built-in test equipment) test, “A/T BITE TEST LRU INTERFACE,” and before further flight do all applicable corrective actions, in accordance with paragraphs 1. through 5. of Boeing Multi-Operator Message MOM-MOM-21-0145-01B(R2), dated March 30, 2021, except as provided in paragraph (h) of this AD. Repeat the test thereafter at intervals not to exceed 2,000 flight hours.
This article is published under license from Avherald.com. © of text by Avherald.com.
Read unlimited articles and receive our daily update briefing. Gain better insights into what is happening in commercial aviation safety.
Support AeroInside by sending a small tip amount.
A Sriwijaya Boeing 737-800, registration PK-CRI performing flight SJ-591 from Makassar to Jakarta (Indonesia), was climbing through about 17,000 feet…
A Sriwijaya Boeing 737-800, registration PK-CRE performing flight SJ-271 from Dili (East Timor) to Denpasar (Indonesia), was climbing out of Dili's…
A Sriwijaya Boeing 737-800, registration PK-CLT performing flight SJ-270 from Denpasar (Indonesia) to Dili (East Timor) with 110 people on board, was…
A Sriwijaya Boeing 737-300, registration PK-CJC performing flight SJ-570 from Sorong to Manokwari (Indonesia) with 146 passengers and 6 crew, landed…
A Sriwijaya Boeing 737-800, registration PK-CMT performing flight SJ-1159 from Guangzhou (China) to Denpasar Bali (Indonesia) with 180 passengers and…
An Emirates Airbus A380-800, registration A6-EUT performing flight EK-30 from London Heathrow,EN (UK) to Dubai (United Arab Emirates) with 447…
A Cargojet Boeing 757-200, registration C-GIAJ performing flight W8-1951 from Cincinnati,KY (USA) to Montreal Mirabel,QC (Canada) with 2 crew, was…
Are you researching aviation incidents? Get access to AeroInside Insights, unlimited read access and receive the daily newsletter.Pick your plan and subscribe
A new way to document and demonstrate airworthiness compliance and aircraft value. Find out more.
Train yourself online in VR with the special course for aviation: "Crisis Communications: Airlines". Find out more.
Never miss an article from AeroInside. Subscribe to our free weekly newsletter and join 4854 existing subscribers.
Popular aircraftAirbus A320
Boeing 737-800 MAX
Popular airlinesAmerican Airlines