May 20 (Reuters) - The helicopter that crashed in Iran

on Sunday, killing the country's president and foreign minister

in mountain fog, was a Bell 212 model, Iranian state media

reported.

A civilian version of the ubiquitous Vietnam War-era UH-1N

"Twin Huey," such helicopters are in wide use globally by both

governments and private operators:

WHAT ARE THE HELICOPTER'S ORIGINS?

Bell Helicopter ( TXT ) developed the aircraft for the Canadian military in the

late 1960s as an upgrade of the original UH-1 Iroquois. The new

design used two turboshaft engines instead of one, giving it

greater carrying capacity. The helicopter was introduced in 1971

and was quickly adopted by both the United States and Canada,

according to U.S. military training documents.

WHAT ARE ITS USES?

As a utility helicopter - the UH in its military designation

represents those words - the Bell 212 is meant to be adaptable

to all sorts of situations, including carrying people,

deploying aerial firefighting gear, ferrying cargo and mounting

weapons.

The Iranian model that crashed on Sunday was configured to

carry government passengers. Bell Helicopter ( TXT ) advertises the

latest version, the Subaru Bell 412, for police use, medical

transport, troop transport, the energy industry and

firefighting. According to its type certification documents with

the European Union Aviation Safety Agency, it can carry 15

people, including the crew.

WHICH ORGANISATIONS OPERATE THE HELICOPTER?

Non-military organisations that fly the Bell 212 include

Japan's Coast Guard; law enforcement agencies and fire

departments in the United States; Thailand's national police;

and many others. It is not clear how many Iran's government

operates, but its air force and navy have a total of 10,

according to FlightGlobal's 2024 World Air Forces directory.

Iran was a major purchaser of Bell and Agusta helicopters

under the Shah, becoming the Middle East's largest military

helicopter power, according to Western reports.

Iran's current fleet includes an Italian-built naval

version, the Agusta Bell AB-212, according to IISS.

The exact origin of the helicopter involved in the crash was

not confirmed but an Iranian source said it was connected to the

Islamic Republic Red Crescent Society. Experts said the few

details available suggested it may be 40 to 50 years old.

HAVE THERE BEEN OTHER INCIDENTS INVOLVING THE BELL 212?

The most recent fatal crash of a Bell 212 was in September

2023, when a privately operated aircraft crashed off the coast

of the United Arab Emirates, according to the Flight Safety

Foundation, a non-profit focusing on aviation safety.

The most recent Iranian crash of the type was in 2018,

killing four people, according to the organisation's database.

In 2015, the same database cited reports that a helicopter

believed to be an AB-212 had crashed near Kashan, killing three.

IRANIAN AVIATION

Iran has kept its civil and military aviation fleets flying

during its isolation since the 1979 revolution through a

combination of smuggled parts and reverse-engineering, according

to Western analysts and people who spoke about the trade

following a nuclear deal later abandoned by Washington.

Its state-owned helicopter services and renovation company,

widely known as PANHA, has presented indigenous models said by

Western analysts to be based on re-engineered Bell aircraft,

though the 212 is not one of the models said to be involved.

"Iran has a reputation for strong technical competence when

it comes to aviation," said Cirium Ascend analyst Paul Hayes.

WILL THERE BE AN INVESTIGATION?

As a domestic state flight, the accident does not

automatically fall under global rules for air accident probes.

Middle East and aviation safety analysts say there is little

chance Iran would turn to outside help for such a politically

sensitive matter on its own territory.

Iran sent black boxes to France following the downing of a

Ukrainian airliner in 2020, but the role of the French BEA was

limited to reading recorders and not investigation or analysis.

"I doubt whether there will be an investigation at all,"

Hayes said, noting the sensitivity of the matter.